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75060b6e |
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05-Mar-2024 |
Thomas Weißschuh <linux@weissschuh.net> |
watchdog/core: remove sysctl handlers from public header The functions are only used in the file where they are defined. Remove them from the header and make them static. Also guard proc_soft_watchdog with a #define-guard as it is not used otherwise. Link: https://lkml.kernel.org/r/20240306-const-sysctl-prep-watchdog-v1-1-bd45da3a41cf@weissschuh.net Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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8d539b84 |
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04-Aug-2023 |
Douglas Anderson <dianders@chromium.org> |
nmi_backtrace: allow excluding an arbitrary CPU The APIs that allow backtracing across CPUs have always had a way to exclude the current CPU. This convenience means callers didn't need to find a place to allocate a CPU mask just to handle the common case. Let's extend the API to take a CPU ID to exclude instead of just a boolean. This isn't any more complex for the API to handle and allows the hardlockup detector to exclude a different CPU (the one it already did a trace for) without needing to find space for a CPU mask. Arguably, this new API also encourages safer behavior. Specifically if the caller wants to avoid tracing the current CPU (maybe because they already traced the current CPU) this makes it more obvious to the caller that they need to make sure that the current CPU ID can't change. [akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub] Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: kernel test robot <lkp@intel.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7ca8fe94 |
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16-Jun-2023 |
Petr Mladek <pmladek@suse.com> |
watchdog/hardlockup: define HARDLOCKUP_DETECTOR_ARCH The HAVE_ prefix means that the code could be enabled. Add another variable for HAVE_HARDLOCKUP_DETECTOR_ARCH without this prefix. It will be set when it should be built. It will make it compatible with the other hardlockup detectors. The change allows to clean up dependencies of PPC_WATCHDOG and HAVE_HARDLOCKUP_DETECTOR_PERF definitions for powerpc. As a result HAVE_HARDLOCKUP_DETECTOR_PERF has the same dependencies on arm, x86, powerpc architectures. Link: https://lkml.kernel.org/r/20230616150618.6073-7-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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47f4cb43 |
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16-Jun-2023 |
Petr Mladek <pmladek@suse.com> |
watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64 The HAVE_ prefix means that the code could be enabled. Add another variable for HAVE_HARDLOCKUP_DETECTOR_SPARC64 without this prefix. It will be set when it should be built. It will make it compatible with the other hardlockup detectors. Before, it is far from obvious that the SPARC64 variant is actually used: $> make ARCH=sparc64 defconfig $> grep HARDLOCKUP_DETECTOR .config CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y After, it is more clear: $> make ARCH=sparc64 defconfig $> grep HARDLOCKUP_DETECTOR .config CONFIG_HAVE_HARDLOCKUP_DETECTOR_BUDDY=y CONFIG_HAVE_HARDLOCKUP_DETECTOR_SPARC64=y CONFIG_HARDLOCKUP_DETECTOR_SPARC64=y Link: https://lkml.kernel.org/r/20230616150618.6073-6-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
a5fcc236 |
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16-Jun-2023 |
Petr Mladek <pmladek@suse.com> |
watchdog/hardlockup: make HAVE_NMI_WATCHDOG sparc64-specific There are several hardlockup detector implementations and several Kconfig values which allow selection and build of the preferred one. CONFIG_HARDLOCKUP_DETECTOR was introduced by the commit 23637d477c1f53acb ("lockup_detector: Introduce CONFIG_HARDLOCKUP_DETECTOR") in v2.6.36. It was a preparation step for introducing the new generic perf hardlockup detector. The existing arch-specific variants did not support the to-be-created generic build configurations, sysctl interface, etc. This distinction was made explicit by the commit 4a7863cc2eb5f98 ("x86, nmi_watchdog: Remove ARCH_HAS_NMI_WATCHDOG and rely on CONFIG_HARDLOCKUP_DETECTOR") in v2.6.38. CONFIG_HAVE_NMI_WATCHDOG was introduced by the commit d314d74c695f967e105 ("nmi watchdog: do not use cpp symbol in Kconfig") in v3.4-rc1. It replaced the above mentioned ARCH_HAS_NMI_WATCHDOG. At that time, it was still used by three architectures, namely blackfin, mn10300, and sparc. The support for blackfin and mn10300 architectures has been completely dropped some time ago. And sparc is the only architecture with the historic NMI watchdog at the moment. And the old sparc implementation is really special. It is always built on sparc64. It used to be always enabled until the commit 7a5c8b57cec93196b ("sparc: implement watchdog_nmi_enable and watchdog_nmi_disable") added in v4.10-rc1. There are only few locations where the sparc64 NMI watchdog interacts with the generic hardlockup detectors code: + implements arch_touch_nmi_watchdog() which is called from the generic touch_nmi_watchdog() + implements watchdog_hardlockup_enable()/disable() to support /proc/sys/kernel/nmi_watchdog + is always preferred over other generic watchdogs, see CONFIG_HARDLOCKUP_DETECTOR + includes asm/nmi.h into linux/nmi.h because some sparc-specific functions are needed in sparc-specific code which includes only linux/nmi.h. The situation became more complicated after the commit 05a4a95279311c3 ("kernel/watchdog: split up config options") and commit 2104180a53698df5 ("powerpc/64s: implement arch-specific hardlockup watchdog") in v4.13-rc1. They introduced HAVE_HARDLOCKUP_DETECTOR_ARCH. It was used for powerpc specific hardlockup detector. It was compatible with the perf one regarding the general boot, sysctl, and programming interfaces. HAVE_HARDLOCKUP_DETECTOR_ARCH was defined as a superset of HAVE_NMI_WATCHDOG. It made some sense because all arch-specific detectors had some common requirements, namely: + implemented arch_touch_nmi_watchdog() + included asm/nmi.h into linux/nmi.h + defined the default value for /proc/sys/kernel/nmi_watchdog But it actually has made things pretty complicated when the generic buddy hardlockup detector was added. Before the generic perf detector was newer supported together with an arch-specific one. But the buddy detector could work on any SMP system. It means that an architecture could support both the arch-specific and buddy detector. As a result, there are few tricky dependencies. For example, CONFIG_HARDLOCKUP_DETECTOR depends on: ((HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_BUDDY) && !HAVE_NMI_WATCHDOG) || HAVE_HARDLOCKUP_DETECTOR_ARCH The problem is that the very special sparc implementation is defined as: HAVE_NMI_WATCHDOG && !HAVE_HARDLOCKUP_DETECTOR_ARCH Another problem is that the meaning of HAVE_NMI_WATCHDOG is far from clear without reading understanding the history. Make the logic less tricky and more self-explanatory by making HAVE_NMI_WATCHDOG specific for the sparc64 implementation. And rename it to HAVE_HARDLOCKUP_DETECTOR_SPARC64. Note that HARDLOCKUP_DETECTOR_PREFER_BUDDY, HARDLOCKUP_DETECTOR_PERF, and HARDLOCKUP_DETECTOR_BUDDY may conflict only with HAVE_HARDLOCKUP_DETECTOR_ARCH. They depend on HARDLOCKUP_DETECTOR and it is not longer enabled when HAVE_NMI_WATCHDOG is set. Link: https://lkml.kernel.org/r/20230616150618.6073-5-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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0c68bda6 |
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16-Jun-2023 |
Petr Mladek <pmladek@suse.com> |
watchdog/hardlockup: declare arch_touch_nmi_watchdog() only in linux/nmi.h arch_touch_nmi_watchdog() needs a different implementation for various hardlockup detector implementations. And it does nothing when any hardlockup detector is not built at all. arch_touch_nmi_watchdog() is declared via linux/nmi.h. And it must be defined as an empty function when there is no hardlockup detector. It is done directly in this header file for the perf and buddy detectors. And it is done in the included asm/linux.h for arch specific detectors. The reason probably is that the arch specific variants build the code using another conditions. For example, powerpc64/sparc64 builds the code when CONFIG_PPC_WATCHDOG is enabled. Another reason might be that these architectures define more functions in asm/nmi.h anyway. However the generic code actually knows when the function will be implemented. It happens when some full featured or the sparc64-specific hardlockup detector is built. In particular, CONFIG_HARDLOCKUP_DETECTOR can be enabled only when a generic or arch-specific full featured hardlockup detector is available. The only exception is sparc64 which can be built even when the global HARDLOCKUP_DETECTOR switch is disabled. The information about sparc64 is a bit complicated. The hardlockup detector is built there when CONFIG_HAVE_NMI_WATCHDOG is set and CONFIG_HAVE_HARDLOCKUP_DETECTOR_ARCH is not set. People might wonder whether this change really makes things easier. The motivation is: + The current logic in linux/nmi.h is far from obvious. For example, arch_touch_nmi_watchdog() is defined as {} when neither CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER nor CONFIG_HAVE_NMI_WATCHDOG is defined. + The change synchronizes the checks in lib/Kconfig.debug and in the generic code. + It is a step that will help cleaning HAVE_NMI_WATCHDOG related checks. The change should not change the existing behavior. Link: https://lkml.kernel.org/r/20230616150618.6073-4-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Douglas Anderson <dianders@chromium.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d3b62ace |
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26-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/buddy: cleanup how watchdog_buddy_check_hardlockup() is called In the patch ("watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs"), we added a call from the common watchdog.c file into the buddy. That call could be done more cleanly. Specifically: 1. If we move the call into watchdog_hardlockup_kick() then it keeps watchdog_timer_fn() simpler. 2. We don't need to pass an "unsigned long" to the buddy for the timer count. In the patch ("watchdog/hardlockup: add a "cpu" param to watchdog_hardlockup_check()") the count was changed to "atomic_t" which is backed by an int, so we should match types. Link: https://lkml.kernel.org/r/20230526184139.6.I006c7d958a1ea5c4e1e4dc44a25596d9bb5fd3ba@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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05e7b558 |
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26-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: remove softlockup comment in touch_nmi_watchdog() In the patch ("watchdog/hardlockup: add comments to touch_nmi_watchdog()") we adjusted some comments for touch_nmi_watchdog(). The comment about the softlockup had a typo and were also felt to be too obvious. Remove it. Link: https://lkml.kernel.org/r/20230526184139.5.Ia593afc9eb12082d55ea6681dc2c5a89677f20a8@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9ec272c5 |
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26-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: keep kernel.nmi_watchdog sysctl as 0444 if probe fails Patch series "watchdog: Cleanup / fixes after buddy series v5 reviews". This patch series attempts to finish resolving the feedback received from Petr Mladek on the v5 series I posted. Probably the only thing that wasn't fully as clean as Petr requested was the Kconfig stuff. I couldn't find a better way to express it without a more major overhaul. In the very least, I renamed "NON_ARCH" to "PERF_OR_BUDDY" in the hopes that will make it marginally better. Nothing in this series is terribly critical and even the bugfixes are small. However, it does cleanup a few things that were pointed out in review. This patch (of 10): The permissions for the kernel.nmi_watchdog sysctl have always been set at compile time despite the fact that a watchdog can fail to probe. Let's fix this and set the permissions based on whether the hardlockup detector actually probed. Link: https://lkml.kernel.org/r/20230527014153.2793931-1-dianders@chromium.org Link: https://lkml.kernel.org/r/20230526184139.1.I0d75971cc52a7283f495aac0bd5c3041aadc734e@changeid Fixes: a994a3147e4c ("watchdog/hardlockup/perf: Implement init time detection of perf") Signed-off-by: Douglas Anderson <dianders@chromium.org> Reported-by: Petr Mladek <pmladek@suse.com> Closes: https://lore.kernel.org/r/ZHCn4hNxFpY5-9Ki@alley Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: "David S. Miller" <davem@davemloft.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
930d8f8d |
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19-May-2023 |
Lecopzer Chen <lecopzer.chen@mediatek.com> |
watchdog/perf: adapt the watchdog_perf interface for async model When lockup_detector_init()->watchdog_hardlockup_probe(), PMU may be not ready yet. E.g. on arm64, PMU is not ready until device_initcall(armv8_pmu_driver_init). And it is deeply integrated with the driver model and cpuhp. Hence it is hard to push this initialization before smp_init(). But it is easy to take an opposite approach and try to initialize the watchdog once again later. The delayed probe is called using workqueues. It need to allocate memory and must be proceed in a normal context. The delayed probe is able to use if watchdog_hardlockup_probe() returns non-zero which means the return code returned when PMU is not ready yet. Provide an API - lockup_detector_retry_init() for anyone who needs to delayed init lockup detector if they had ever failed at lockup_detector_init(). The original assumption is: nobody should use delayed probe after lockup_detector_check() which has __init attribute. That is, anyone uses this API must call between lockup_detector_init() and lockup_detector_check(), and the caller must have __init attribute Link: https://lkml.kernel.org/r/20230519101840.v5.16.If4ad5dd5d09fb1309cebf8bcead4b6a5a7758ca7@changeid Reviewed-by: Petr Mladek <pmladek@suse.com> Co-developed-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Suggested-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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b17aa959 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/perf: add a weak function for an arch to detect if perf can use NMIs On arm64, NMI support needs to be detected at runtime. Add a weak function to the perf hardlockup detector so that an architecture can implement it to detect whether NMIs are available. Link: https://lkml.kernel.org/r/20230519101840.v5.15.Ic55cb6f90ef5967d8aaa2b503a4e67c753f64d3a@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1f423c90 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs Implement a hardlockup detector that doesn't doesn't need any extra arch-specific support code to detect lockups. Instead of using something arch-specific we will use the buddy system, where each CPU watches out for another one. Specifically, each CPU will use its softlockup hrtimer to check that the next CPU is processing hrtimer interrupts by verifying that a counter is increasing. NOTE: unlike the other hard lockup detectors, the buddy one can't easily show what's happening on the CPU that locked up just by doing a simple backtrace. It relies on some other mechanism in the system to get information about the locked up CPUs. This could be support for NMI backtraces like [1], it could be a mechanism for printing the PC of locked CPUs at panic time like [2] / [3], or it could be something else. Even though that means we still rely on arch-specific code, this arch-specific code seems to often be implemented even on architectures that don't have a hardlockup detector. This style of hardlockup detector originated in some downstream Android trees and has been rebased on / carried in ChromeOS trees for quite a long time for use on arm and arm64 boards. Historically on these boards we've leveraged mechanism [2] / [3] to get information about hung CPUs, but we could move to [1]. Although the original motivation for the buddy system was for use on systems without an arch-specific hardlockup detector, it can still be useful to use even on systems that _do_ have an arch-specific hardlockup detector. On x86, for instance, there is a 24-part patch series [4] in progress switching the arch-specific hard lockup detector from a scarce perf counter to a less-scarce hardware resource. Potentially the buddy system could be a simpler alternative to free up the perf counter but still get hard lockup detection. Overall, pros (+) and cons (-) of the buddy system compared to an arch-specific hardlockup detector (which might be implemented using perf): + The buddy system is usable on systems that don't have an arch-specific hardlockup detector, like arm32 and arm64 (though it's being worked on for arm64 [5]). + The buddy system may free up scarce hardware resources. + If a CPU totally goes out to lunch (can't process NMIs) the buddy system could still detect the problem (though it would be unlikely to be able to get a stack trace). + The buddy system uses the same timer function to pet the hardlockup detector on the running CPU as it uses to detect hardlockups on other CPUs. Compared to other hardlockup detectors, this means it generates fewer interrupts and thus is likely better able to let CPUs stay idle longer. - If all CPUs are hard locked up at the same time the buddy system can't detect it. - If we don't have SMP we can't use the buddy system. - The buddy system needs an arch-specific mechanism (possibly NMI backtrace) to get info about the locked up CPU. [1] https://lore.kernel.org/r/20230419225604.21204-1-dianders@chromium.org [2] https://issuetracker.google.com/172213129 [3] https://docs.kernel.org/trace/coresight/coresight-cpu-debug.html [4] https://lore.kernel.org/lkml/20230301234753.28582-1-ricardo.neri-calderon@linux.intel.com/ [5] https://lore.kernel.org/linux-arm-kernel/20220903093415.15850-1-lecopzer.chen@mediatek.com/ Link: https://lkml.kernel.org/r/20230519101840.v5.14.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Signed-off-by: Guenter Roeck <groeck@chromium.org> Signed-off-by: Tzung-Bi Shih <tzungbi@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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d9b3629a |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: have the perf hardlockup use __weak functions more cleanly The fact that there watchdog_hardlockup_enable(), watchdog_hardlockup_disable(), and watchdog_hardlockup_probe() are declared __weak means that the configured hardlockup detector can define non-weak versions of those functions if it needs to. Instead of doing this, the perf hardlockup detector hooked itself into the default __weak implementation, which was a bit awkward. Clean this up. From comments, it looks as if the original design was done because the __weak function were expected to implemented by the architecture and not by the configured hardlockup detector. This got awkward when we tried to add the buddy lockup detector which was not arch-specific but wanted to hook into those same functions. This is not expected to have any functional impact. Link: https://lkml.kernel.org/r/20230519101840.v5.13.I847d9ec852449350997ba00401d2462a9cb4302b@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
df95d308 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: rename some "NMI watchdog" constants/function Do a search and replace of: - NMI_WATCHDOG_ENABLED => WATCHDOG_HARDLOCKUP_ENABLED - SOFT_WATCHDOG_ENABLED => WATCHDOG_SOFTOCKUP_ENABLED - watchdog_nmi_ => watchdog_hardlockup_ - nmi_watchdog_available => watchdog_hardlockup_available - nmi_watchdog_user_enabled => watchdog_hardlockup_user_enabled - soft_watchdog_user_enabled => watchdog_softlockup_user_enabled - NMI_WATCHDOG_DEFAULT => WATCHDOG_HARDLOCKUP_DEFAULT Then update a few comments near where names were changed. This is specifically to make it less confusing when we want to introduce the buddy hardlockup detector, which isn't using NMIs. As part of this, we sanitized a few names for consistency. [trix@redhat.com: make variables static] Link: https://lkml.kernel.org/r/20230525162822.1.I0fb41d138d158c9230573eaa37dc56afa2fb14ee@changeid Link: https://lkml.kernel.org/r/20230519101840.v5.12.I91f7277bab4bf8c0cb238732ed92e7ce7bbd71a6@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Tom Rix <trix@redhat.com> Reviewed-by: Tom Rix <trix@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
ed92e1ef |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: move perf hardlockup watchdog petting to watchdog.c In preparation for the buddy hardlockup detector, which wants the same petting logic as the current perf hardlockup detector, move the code to watchdog.c. While doing this, rename the global variable to match others nearby. As part of this change we have to change the code to account for the fact that the CPU we're running on might be different than the one we're checking. Currently the code in watchdog.c is guarded by CONFIG_HARDLOCKUP_DETECTOR_PERF, which makes this change seem silly. However, a future patch will change this. Link: https://lkml.kernel.org/r/20230519101840.v5.11.I00dfd6386ee00da25bf26d140559a41339b53e57@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
77c12fc9 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: add a "cpu" param to watchdog_hardlockup_check() In preparation for the buddy hardlockup detector where the CPU checking for lockup might not be the currently running CPU, add a "cpu" parameter to watchdog_hardlockup_check(). As part of this change, make hrtimer_interrupts an atomic_t since now the CPU incrementing the value and the CPU reading the value might be different. Technially this could also be done with just READ_ONCE and WRITE_ONCE, but atomic_t feels a little cleaner in this case. While hrtimer_interrupts is made atomic_t, we change hrtimer_interrupts_saved from "unsigned long" to "int". The "int" is needed to match the data type backing atomic_t for hrtimer_interrupts. Even if this changes us from 64-bits to 32-bits (which I don't think is true for most compilers), it doesn't really matter. All we ever do is increment it every few seconds and compare it to an old value so 32-bits is fine (even 16-bits would be). The "signed" vs "unsigned" also doesn't matter for simple equality comparisons. hrtimer_interrupts_saved is _not_ switched to atomic_t nor even accessed with READ_ONCE / WRITE_ONCE. The hrtimer_interrupts_saved is always consistently accessed with the same CPU. NOTE: with the upcoming "buddy" detector there is one special case. When a CPU goes offline/online then we can change which CPU is the one to consistently access a given instance of hrtimer_interrupts_saved. We still can't end up with a partially updated hrtimer_interrupts_saved, however, because we end up petting all affected CPUs to make sure the new and old CPU can't end up somehow read/write hrtimer_interrupts_saved at the same time. Link: https://lkml.kernel.org/r/20230519101840.v5.10.I3a7d4dd8c23ac30ee0b607d77feb6646b64825c0@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
81972551 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: move perf hardlockup checking/panic to common watchdog.c The perf hardlockup detector works by looking at interrupt counts and seeing if they change from run to run. The interrupt counts are managed by the common watchdog code via its watchdog_timer_fn(). Currently the API between the perf detector and the common code is a function: is_hardlockup(). When the hard lockup detector sees that function return true then it handles printing out debug info and inducing a panic if necessary. Let's change the API a little bit in preparation for the buddy hardlockup detector. The buddy hardlockup detector wants to print nearly the same debug info and have nearly the same panic behavior. That means we want to move all that code to the common file. For now, the code in the common file will only be there if the perf hardlockup detector is enabled, but eventually it will be selected by a common config. Right now, this _just_ moves the code from the perf detector file to the common file and changes the names. It doesn't make the changes that the buddy hardlockup detector will need and doesn't do any style cleanups. A future patch will do cleanup to make it more obvious what changed. With the above, we no longer have any callers of is_hardlockup() outside of the "watchdog.c" file, so we can remove it from the header, make it static, and move it to the same "#ifdef" block as our new watchdog_hardlockup_check(). While doing this, it can be noted that even if no hardlockup detectors were configured the existing code used to still have the code for counting/checking "hrtimer_interrupts" even if the perf hardlockup detector wasn't configured. We didn't need to do that, so move all the "hrtimer_interrupts" counting to only be there if the perf hardlockup detector is configured as well. This change is expected to be a no-op. Link: https://lkml.kernel.org/r/20230519101840.v5.8.Id4133d3183e798122dc3b6205e7852601f289071@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
8b5c59a9 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/hardlockup: add comments to touch_nmi_watchdog() In preparation for the buddy hardlockup detector, add comments to touch_nmi_watchdog() to make it obvious that it touches the configured hardlockup detector regardless of whether it's backed by an NMI. Also note that arch_touch_nmi_watchdog() may not be architecture-specific. Ideally, we'd like to rename these functions but that is a fairly disruptive change touching a lot of drivers. After discussion [1] the plan is to defer this until a good time. [1] https://lore.kernel.org/r/ZFy0TX1tfhlH8gxj@alley [akpm@linux-foundation.org: comment changes, per Petr] Link: https://lkml.kernel.org/r/ZGyONWPXpE1DcxA5@alley Link: https://lkml.kernel.org/r/20230519101840.v5.6.I4e47cbfa1bb2ebbcdb5ca16817aa2887f15dc82c@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
73021118 |
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19-May-2023 |
Lecopzer Chen <lecopzer.chen@mediatek.com> |
watchdog/hardlockup: change watchdog_nmi_enable() to void Nobody cares about the return value of watchdog_nmi_enable(), changing its prototype to void. Link: https://lkml.kernel.org/r/20230519101840.v5.4.Ic3a19b592eb1ac4c6f6eade44ffd943e8637b6e5@changeid Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Nicholas Piggin <npiggin@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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#
5e008df1 |
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19-May-2023 |
Douglas Anderson <dianders@chromium.org> |
watchdog/perf: define dummy watchdog_update_hrtimer_threshold() on correct config Patch series "watchdog/hardlockup: Add the buddy hardlockup detector", v5. This patch series adds the "buddy" hardlockup detector. In brief, the buddy hardlockup detector can detect hardlockups without arch-level support by having CPUs checkup on a "buddy" CPU periodically. Given the new design of this patch series, testing all combinations is fairly difficult. I've attempted to make sure that all combinations of CONFIG_ options are good, but it wouldn't surprise me if I missed something. I apologize in advance and I'll do my best to fix any problems that are found. This patch (of 18): The real watchdog_update_hrtimer_threshold() is defined in kernel/watchdog_hld.c. That file is included if CONFIG_HARDLOCKUP_DETECTOR_PERF and the function is defined in that file if CONFIG_HARDLOCKUP_CHECK_TIMESTAMP. The dummy version of the function in "nmi.h" didn't get that quite right. While this doesn't appear to be a huge deal, it's nice to make it consistent. It doesn't break builds because CHECK_TIMESTAMP is only defined by x86 so others don't get a double definition, and x86 uses perf lockup detector, so it gets the out of line version. Link: https://lkml.kernel.org/r/20230519101840.v5.18.Ia44852044cdcb074f387e80df6b45e892965d4a1@changeid Link: https://lkml.kernel.org/r/20230519101840.v5.1.I8cbb2f4fa740528fcfade4f5439b6cdcdd059251@changeid Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes") Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Cc: Colin Cross <ccross@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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344da544 |
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16-Dec-2022 |
Paul E. McKenney <paulmck@kernel.org> |
x86/nmi: Print reasons why backtrace NMIs are ignored Instrument nmi_trigger_cpumask_backtrace() to dump out diagnostics based on evidence accumulated by exc_nmi(). These diagnostics are dumped for CPUs that ignored an NMI backtrace request for more than 10 seconds. [ paulmck: Apply Ingo Molnar feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: <x86@kernel.org> Reviewed-by: Ingo Molnar <mingo@kernel.org>
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7c56a873 |
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13-Jul-2022 |
Laurent Dufour <ldufour@linux.ibm.com> |
watchdog: export lockup_detector_reconfigure In some circumstances it may be interesting to reconfigure the watchdog from inside the kernel. On PowerPC, this may helpful before and after a LPAR migration (LPM) is initiated, because it implies some latencies, watchdog, and especially NMI watchdog is expected to be triggered during this operation. Reconfiguring the watchdog with a factor, would prevent it to happen too frequently during LPM. Rename lockup_detector_reconfigure() as __lockup_detector_reconfigure() and create a new function lockup_detector_reconfigure() calling __lockup_detector_reconfigure() under the protection of watchdog_mutex. Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> [mpe: Squash in build fix from Laurent, reported by Sachin] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220713154729.80789-3-ldufour@linux.ibm.com
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32927393 |
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24-Apr-2020 |
Christoph Hellwig <hch@lst.de> |
sysctl: pass kernel pointers to ->proc_handler Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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81bd415c |
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06-Jun-2018 |
Mathieu Malaterre <malat@debian.org> |
watchdog/core: Add missing prototypes for weak functions The split out of the hard lockup detector exposed two new weak functions, but no prototypes for them, which triggers the build warning: kernel/watchdog.c:109:12: warning: no previous prototype for ‘watchdog_nmi_enable’ [-Wmissing-prototypes] kernel/watchdog.c:115:13: warning: no previous prototype for ‘watchdog_nmi_disable’ [-Wmissing-prototypes] Add the prototypes. Fixes: 73ce0511c436 ("kernel/watchdog.c: move hardlockup detector to separate file") Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Babu Moger <babu.moger@oracle.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180606194232.17653-1-malat@debian.org
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#
aef92a8b |
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10-Jul-2018 |
Peter Zijlstra <peterz@infradead.org> |
watchdog/softlockup: Fix the SOFTLOCKUP_DETECTOR=n build I got confused by all the various CONFIG options here about and conflated CONFIG_LOCKUP_DETECTOR and CONFIG_SOFTLOCKUP_DETECTOR. This results in a build failure for: CONFIG_LOCKUP_DETECTOR=y && CONFIG_SOFTLOCKUP_DETECTOR=n As reported by Abdul. Reported-and-tested-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-next <linux-next@vger.kernel.org> Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org> Cc: mpe <mpe@ellerman.id.au> Cc: sachinp <sachinp@linux.vnet.ibm.com> Cc: stephen Rothwell <sfr@canb.auug.org.au> Fixes: 9cf57731b63e ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work") Link: http://lkml.kernel.org/r/20180710114210.GI2476@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
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#
9cf57731 |
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07-Jun-2018 |
Peter Zijlstra <peterz@infradead.org> |
watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work Oleg suggested to replace the "watchdog/%u" threads with cpu_stop_work. That removes one thread per CPU while at the same time fixes softlockup vs SCHED_DEADLINE. But more importantly, it does away with the single smpboot_update_cpumask_percpu_thread() user, which allows cleanups/shrinkage of the smpboot interface. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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b2441318 |
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01-Nov-2017 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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34ddaa3e |
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03-Oct-2017 |
Thomas Gleixner <tglx@linutronix.de> |
powerpc/watchdog: Make use of watchdog_nmi_probe() The rework of the core hotplug code triggers the WARN_ON in start_wd_cpu() on powerpc because it is called multiple times for the boot CPU. The first call is via: start_wd_on_cpu+0x80/0x2f0 watchdog_nmi_reconfigure+0x124/0x170 softlockup_reconfigure_threads+0x110/0x130 lockup_detector_init+0xbc/0xe0 kernel_init_freeable+0x18c/0x37c kernel_init+0x2c/0x160 ret_from_kernel_thread+0x5c/0xbc And then again via the CPU hotplug registration: start_wd_on_cpu+0x80/0x2f0 cpuhp_invoke_callback+0x194/0x620 cpuhp_thread_fun+0x7c/0x1b0 smpboot_thread_fn+0x290/0x2a0 kthread+0x168/0x1b0 ret_from_kernel_thread+0x5c/0xbc This can be avoided by setting up the cpu hotplug state with nocalls and move the initialization to the watchdog_nmi_probe() function. That initializes the hotplug callbacks without invoking the callback and the following core initialization function then configures the watchdog for the online CPUs (in this case CPU0) via softlockup_reconfigure_threads(). Reported-and-tested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: linuxppc-dev@lists.ozlabs.org
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6b9dc480 |
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01-Oct-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core, powerpc: Replace watchdog_nmi_reconfigure() The recent cleanup of the watchdog code split watchdog_nmi_reconfigure() into two stages. One to stop the NMI and one to restart it after reconfiguration. That was done by adding a boolean 'run' argument to the code, which is functionally correct but not necessarily a piece of art. Replace it by two explicit functions: watchdog_nmi_stop() and watchdog_nmi_start(). Fixes: 6592ad2fcc8f ("watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage") Requested-by: Linus 'Nursing his pet-peeve' Torvalds <torvalds@linuxfoundation.org> Signed-off-by: Thomas 'Mopping up garbage' Gleixner <tglx@linutronix.de> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Don Zickus <dzickus@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710021957480.2114@nanos
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2a1b8ee4 |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/hardlockup/perf: Implement CPU enable replacement watchdog_nmi_enable() is an unparseable mess, Provide a clean perf specific implementation, which will be used when the existing setup/teardown mess is replaced. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194148.180215498@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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178b9f7a |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/hardlockup/perf: Implement init time perf validation The watchdog tries to create perf events even after it figured out that perf is not functional or the requested event is not supported. That's braindead as this can be done once at init time and if not supported the NMI watchdog can be turned off unconditonally. Implement the perf hardlockup detector functionality for that. This creates a new event create function, which will replace the unholy mess of the existing one in later patches. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194148.019090547@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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6592ad2f |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core, powerpc: Make watchdog_nmi_reconfigure() two stage Both the perf reconfiguration and the powerpc watchdog_nmi_reconfigure() need to be done in two steps. 1) Stop all NMIs 2) Read the new parameters and start NMIs Right now watchdog_nmi_reconfigure() is a combination of both. To allow a clean reconfiguration add a 'run' argument and split the functionality in powerpc. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20170912194147.862865570@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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7feeb9cd |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/sysctl: Clean up sysctl variable name space Reflect that these variables are user interface related and remove the whitespace damage in the sysctl table while at it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194147.783210221@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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51d4052b |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/sysctl: Get rid of the #ifdeffery The sysctl of the nmi_watchdog file prevents writes by setting: min = max = 0 if none of the users is enabled. That involves ifdeffery and is competely non obvious. If none of the facilities is enabeld, then the file can simply be made read only. Move the ifdeffery into the header and use a constant for file permissions. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194147.706073616@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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3b371b59 |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core: Clean up header mess Having the same #ifdef in various places does not make it more readable. Collect stuff into one place. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194147.627096864@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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01f0a027 |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core: Remove the park_in_progress obfuscation Commit: b94f51183b06 ("kernel/watchdog: prevent false hardlockup on overloaded system") tries to fix the following issue: proc_write() set_sample_period() <--- New sample period becoms visible <----- Broken starts proc_watchdog_update() watchdog_enable_all_cpus() watchdog_hrtimer_fn() update_watchdog_all_cpus() restart_timer(sample_period) watchdog_park_threads() thread->park() disable_nmi() <----- Broken ends The reason why this is broken is that the update of the watchdog threshold becomes immediately effective and visible for the hrtimer function which uses that value to rearm the timer. But the NMI/perf side still uses the old value up to the point where it is disabled. If the rate has been lowered then the NMI can run fast enough to 'detect' a hard lockup because the timer has not fired due to the longer period. The patch 'fixed' this by adding a variable: proc_write() set_sample_period() <----- Broken starts proc_watchdog_update() watchdog_enable_all_cpus() watchdog_hrtimer_fn() update_watchdog_all_cpus() restart_timer(sample_period) watchdog_park_threads() park_in_progress = 1 <----- Broken ends nmi_watchdog() if (park_in_progress) return; The only effect of this variable was to make the window where the breakage can hit small enough that it was not longer observable in testing. From a correctness point of view it is a pointless bandaid which merily papers over the root cause: the unsychronized update of the variable. Looking deeper into the related code pathes unearthed similar problems in the watchdog_start()/stop() functions. watchdog_start() perf_nmi_event_start() hrtimer_start() watchdog_stop() hrtimer_cancel() perf_nmi_event_stop() In both cases the call order is wrong because if the tasks gets preempted or the VM gets scheduled out long enough after the first call, then there is a chance that the next NMI will see a stale hrtimer interrupt count and trigger a false positive hard lockup splat. Get rid of park_in_progress so the code can be gradually deobfuscated and pruned from several layers of duct tape papering over the root cause, which has been either ignored or not understood at all. Once this is removed the underlying problem will be fixed by rewriting the proc interface to do a proper synchronized update. Address the start/stop() ordering problem as well by reverting the call order, so this part is at least correct now. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1709052038270.2393@nanos Signed-off-by: Ingo Molnar <mingo@kernel.org>
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941154bd |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/hardlockup/perf: Prevent CPU hotplug deadlock The following deadlock is possible in the watchdog hotplug code: cpus_write_lock() ... takedown_cpu() smpboot_park_threads() smpboot_park_thread() kthread_park() ->park() := watchdog_disable() watchdog_nmi_disable() perf_event_release_kernel(); put_event() _free_event() ->destroy() := hw_perf_event_destroy() x86_release_hardware() release_ds_buffers() get_online_cpus() when a per cpu watchdog perf event is destroyed which drops the last reference to the PMU hardware. The cleanup code there invokes get_online_cpus() which instantly deadlocks because the hotplug percpu rwsem is write locked. To solve this add a deferring mechanism: cpus_write_lock() kthread_park() watchdog_nmi_disable(deferred) perf_event_disable(event); move_event_to_deferred(event); .... cpus_write_unlock() cleaup_deferred_events() perf_event_release_kernel() This is still properly serialized against concurrent hotplug via the cpu_add_remove_lock, which is held by the task which initiated the hotplug event. This is also used to handle event destruction when the watchdog threads are parked via other mechanisms than CPU hotplug. Analyzed-by: Peter Zijlstra <peterz@infradead.org> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194146.884469246@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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5490125d |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core: Remove broken suspend/resume interfaces This interface has several issues: - It's causing recursive locking of the hotplug lock. - It's complete overkill to teardown all threads and then recreate them The same can be achieved with the simple hardlockup_detector_perf_stop / restart() interfaces. The abuse from the busy looping poweroff() loop of PARISC has been solved as well. Remove the cruft. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194146.487537732@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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6554fd8c |
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12-Sep-2017 |
Thomas Gleixner <tglx@linutronix.de> |
watchdog/core: Provide interface to stop from poweroff() PARISC has a a busy looping power off routine. If the watchdog is enabled the watchdog timer will still fire, but the thread is not running, which causes the softlockup watchdog to trigger. Provide a interface which allows to turn the watchdog off. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Helge Deller <deller@gmx.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: linux-parisc@vger.kernel.org Link: http://lkml.kernel.org/r/20170912194146.327343752@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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d0b6e0a8 |
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12-Sep-2017 |
Peter Zijlstra <peterz@infradead.org> |
watchdog/hardlockup: Provide interface to stop/restart perf events Provide an interface to stop and restart perf NMI watchdog events on all CPUs. This is only usable during init and especially for handling the perf HT bug on Intel machines. It's safe to use it this way as nothing can start/stop the NMI watchdog in parallel. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Don Zickus <dzickus@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Ulrich Obergfell <uobergfe@redhat.com> Link: http://lkml.kernel.org/r/20170912194146.167649596@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
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7edaeb68 |
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15-Aug-2017 |
Thomas Gleixner <tglx@linutronix.de> |
kernel/watchdog: Prevent false positives with turbo modes The hardlockup detector on x86 uses a performance counter based on unhalted CPU cycles and a periodic hrtimer. The hrtimer period is about 2/5 of the performance counter period, so the hrtimer should fire 2-3 times before the performance counter NMI fires. The NMI code checks whether the hrtimer fired since the last invocation. If not, it assumess a hard lockup. The calculation of those periods is based on the nominal CPU frequency. Turbo modes increase the CPU clock frequency and therefore shorten the period of the perf/NMI watchdog. With extreme Turbo-modes (3x nominal frequency) the perf/NMI period is shorter than the hrtimer period which leads to false positives. A simple fix would be to shorten the hrtimer period, but that comes with the side effect of more frequent hrtimer and softlockup thread wakeups, which is not desired. Implement a low pass filter, which checks the perf/NMI period against kernel time. If the perf/NMI fires before 4/5 of the watchdog period has elapsed then the event is ignored and postponed to the next perf/NMI. That solves the problem and avoids the overhead of shorter hrtimer periods and more frequent softlockup thread wakeups. Fixes: 58687acba592 ("lockup_detector: Combine nmi_watchdog and softlockup detector") Reported-and-tested-by: Kan Liang <Kan.liang@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: dzickus@redhat.com Cc: prarit@redhat.com Cc: ak@linux.intel.com Cc: babu.moger@oracle.com Cc: peterz@infradead.org Cc: eranian@google.com Cc: acme@redhat.com Cc: stable@vger.kernel.org Cc: atomlin@redhat.com Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1708150931310.1886@nanos
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05a4a952 |
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12-Jul-2017 |
Nicholas Piggin <npiggin@gmail.com> |
kernel/watchdog: split up config options Split SOFTLOCKUP_DETECTOR from LOCKUP_DETECTOR, and split HARDLOCKUP_DETECTOR_PERF from HARDLOCKUP_DETECTOR. LOCKUP_DETECTOR implies the general boot, sysctl, and programming interfaces for the lockup detectors. An architecture that wants to use a hard lockup detector must define HAVE_HARDLOCKUP_DETECTOR_PERF or HAVE_HARDLOCKUP_DETECTOR_ARCH. Alternatively an arch can define HAVE_NMI_WATCHDOG, which provides the minimum arch_touch_nmi_watchdog, and it otherwise does its own thing and does not implement the LOCKUP_DETECTOR interfaces. sparc is unusual in that it has started to implement some of the interfaces, but not fully yet. It should probably be converted to a full HAVE_HARDLOCKUP_DETECTOR_ARCH. [npiggin@gmail.com: fix] Link: http://lkml.kernel.org/r/20170617223522.66c0ad88@roar.ozlabs.ibm.com Link: http://lkml.kernel.org/r/20170616065715.18390-4-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Don Zickus <dzickus@redhat.com> Reviewed-by: Babu Moger <babu.moger@oracle.com> Tested-by: Babu Moger <babu.moger@oracle.com> [sparc] Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f2e0cff8 |
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12-Jul-2017 |
Nicholas Piggin <npiggin@gmail.com> |
kernel/watchdog: introduce arch_touch_nmi_watchdog() For architectures that define HAVE_NMI_WATCHDOG, instead of having them provide the complete touch_nmi_watchdog() function, just have them provide arch_touch_nmi_watchdog(). This gives the generic code more flexibility in implementing this function, and arch implementations don't miss out on touching the softlockup watchdog or other generic details. Link: http://lkml.kernel.org/r/20170616065715.18390-3-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Don Zickus <dzickus@redhat.com> Reviewed-by: Babu Moger <babu.moger@oracle.com> Tested-by: Babu Moger <babu.moger@oracle.com> [sparc] Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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24bb4461 |
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12-Jul-2017 |
Nicholas Piggin <npiggin@gmail.com> |
kernel/watchdog: remove unused declaration Patch series "Improve watchdog config for arch watchdogs", v4. A series to make the hardlockup watchdog more easily replaceable by arch code. The last patch provides some justification for why we want to do this (existing sparc watchdog is another that could benefit). This patch (of 5): Remove unused declaration. Link: http://lkml.kernel.org/r/20170616065715.18390-2-npiggin@gmail.com Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Don Zickus <dzickus@redhat.com> Reviewed-by: Babu Moger <babu.moger@oracle.com> Tested-by: Babu Moger <babu.moger@oracle.com> [sparc] Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d151b27d |
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02-Feb-2017 |
Ingo Molnar <mingo@kernel.org> |
sched/headers: Move softlockup detector watchdog methods to <linux/nmi.h> These methods don't belong into <linux/sched.h>, they are neither directly related to task_struct or are scheduler functionality. Put them next to the other watchdog methods in <linux/nmi.h>. ( Arguably that header's name is a misnomer, and this patch makes it more so - but it should be renamed in another patch. ) Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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b94f5118 |
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24-Jan-2017 |
Don Zickus <dzickus@redhat.com> |
kernel/watchdog: prevent false hardlockup on overloaded system On an overloaded system, it is possible that a change in the watchdog threshold can be delayed long enough to trigger a false positive. This can easily be achieved by having a cpu spinning indefinitely on a task, while another cpu updates watchdog threshold. What happens is while trying to park the watchdog threads, the hrtimers on the other cpus trigger and reprogram themselves with the new slower watchdog threshold. Meanwhile, the nmi watchdog is still programmed with the old faster threshold. Because the one cpu is blocked, it prevents the thread parking on the other cpus from completing, which is needed to shutdown the nmi watchdog and reprogram it correctly. As a result, a false positive from the nmi watchdog is reported. Fix this by setting a park_in_progress flag to block all lockups until the parking is complete. Fix provided by Ulrich Obergfell. [akpm@linux-foundation.org: s/park_in_progress/watchdog_park_in_progress/] Link: http://lkml.kernel.org/r/1481041033-192236-1-git-send-email-dzickus@redhat.com Signed-off-by: Don Zickus <dzickus@redhat.com> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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249e52e3 |
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14-Dec-2016 |
Babu Moger <babu.moger@oracle.com> |
kernel/watchdog.c: move shared definitions to nmi.h Patch series "Clean up watchdog handlers", v2. This is an attempt to cleanup watchdog handlers. Right now, kernel/watchdog.c implements both softlockup and hardlockup detectors. Softlockup code is generic. Hardlockup code is arch specific. Some architectures don't use hardlockup detectors. They use their own watchdog detectors. To make both these combination work, we have numerous #ifdefs in kernel/watchdog.c. We are trying here to make these handlers independent of each other. Also provide an interface for architectures to implement their own handlers. watchdog_nmi_enable and watchdog_nmi_disable will be defined as weak such that architectures can override its definitions. Thanks to Don Zickus for his suggestions. Here are our previous discussions http://www.spinics.net/lists/sparclinux/msg16543.html http://www.spinics.net/lists/sparclinux/msg16441.html This patch (of 3): Move shared macros and definitions to nmi.h so that watchdog.c, new file watchdog_hld.c or any other architecture specific handler can use those definitions. Link: http://lkml.kernel.org/r/1478034826-43888-2-git-send-email-babu.moger@oracle.com Signed-off-by: Babu Moger <babu.moger@oracle.com> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Andi Kleen <andi@firstfloor.org> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Cc: Josh Hunt <johunt@akamai.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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9a01c3ed |
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07-Oct-2016 |
Chris Metcalf <cmetcalf@mellanox.com> |
nmi_backtrace: add more trigger_*_cpu_backtrace() methods Patch series "improvements to the nmi_backtrace code" v9. This patch series modifies the trigger_xxx_backtrace() NMI-based remote backtracing code to make it more flexible, and makes a few small improvements along the way. The motivation comes from the task isolation code, where there are scenarios where we want to be able to diagnose a case where some cpu is about to interrupt a task-isolated cpu. It can be helpful to see both where the interrupting cpu is, and also an approximation of where the cpu that is being interrupted is. The nmi_backtrace framework allows us to discover the stack of the interrupted cpu. I've tested that the change works as desired on tile, and build-tested x86, arm, mips, and sparc64. For x86 I confirmed that the generic cpuidle stuff as well as the architecture-specific routines are in the new cpuidle section. For arm, mips, and sparc I just build-tested it and made sure the generic cpuidle routines were in the new cpuidle section, but I didn't attempt to figure out which the platform-specific idle routines might be. That might be more usefully done by someone with platform experience in follow-up patches. This patch (of 4): Currently you can only request a backtrace of either all cpus, or all cpus but yourself. It can also be helpful to request a remote backtrace of a single cpu, and since we want that, the logical extension is to support a cpumask as the underlying primitive. This change modifies the existing lib/nmi_backtrace.c code to take a cpumask as its basic primitive, and modifies the linux/nmi.h code to use the new "cpumask" method instead. The existing clients of nmi_backtrace (arm and x86) are converted to using the new cpumask approach in this change. The other users of the backtracing API (sparc64 and mips) are converted to use the cpumask approach rather than the all/allbutself approach. The mips code ignored the "include_self" boolean but with this change it will now also dump a local backtrace if requested. Link: http://lkml.kernel.org/r/1472487169-14923-2-git-send-email-cmetcalf@mellanox.com Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com> Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm] Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Russell King <linux@arm.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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44530d58 |
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10-Jul-2016 |
Ingo Molnar <mingo@kernel.org> |
Revert "perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86" This reverts commit 2c95afc1e83d93fac3be6923465e1753c2c53b0a. Stephane reported the following regression: > Since Andi added: > > commit 2c95afc1e83d93fac3be6923465e1753c2c53b0a > Author: Andi Kleen <ak@linux.intel.com> > Date: Thu Jun 9 06:14:38 2016 -0700 > > perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86 > > $ perf stat -e ref-cycles ls > <not counted> .... > > fails systematically because the ref-cycles is now used by the > watchdog and given this is a system-wide pinned event, it monopolizes > the fixed counter 2 which is the only counter able to measure this event. Since the next merge window is near, fix the regression for now by reverting the commit. Reported-by: Stephane Eranian <eranian@google.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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2c95afc1 |
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09-Jun-2016 |
Andi Kleen <ak@linux.intel.com> |
perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86 The NMI watchdog uses either the fixed cycles or a generic cycles counter. This causes a lot of conflicts with users of the PMU who want to run a full group including the cycles fixed counter, for example the --topdown support recently added to perf stat. The code needs to fall back to not use groups, which can cause measurement inaccuracy due to multiplexing errors. This patch switches the NMI watchdog to use reference cycles on Intel systems. This is actually more accurate than cycles, because cycles can tick faster than the measured CPU Frequency due to Turbo mode. The ref cycles always tick at their frequency, or slower when the system is idling. That means the NMI watchdog can never expire too early, unlike with cycles. The reference cycles tick roughly at the frequency of the TSC, so the same period computation can be used. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: acme@kernel.org Cc: jolsa@kernel.org Link: http://lkml.kernel.org/r/1465478079-19993-1-git-send-email-andi@firstfloor.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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f09e3f4f |
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22-Mar-2016 |
Yaowei Bai <baiyaowei@cmss.chinamobile.com> |
x86/apic: Remove declaration of unused hw_nmi_is_cpu_stuck Commit 10f9014912 ("x86: Cleanup hw_nmi.c cruft") removed unused code in the hw_nmi.c file because of the redesign of the hardlockup watchdog but left declaration of hw_nmi_is_cpu_stuck in linux/nmi.h, so remvoe it. Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Link: http://lkml.kernel.org/r/1458697210-3027-1-git-send-email-baiyaowei@cmss.chinamobile.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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55537871 |
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05-Nov-2015 |
Jiri Kosina <jkosina@suse.cz> |
kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup In many cases of hardlockup reports, it's actually not possible to know why it triggered, because the CPU that got stuck is usually waiting on a resource (with IRQs disabled) in posession of some other CPU is holding. IOW, we are often looking at the stacktrace of the victim and not the actual offender. Introduce sysctl / cmdline parameter that makes it possible to have hardlockup detector perform all-CPU backtrace. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Acked-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ec6a9066 |
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04-Sep-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: rename watchdog_suspend() and watchdog_resume() Rename watchdog_suspend() to lockup_detector_suspend() and watchdog_resume() to lockup_detector_resume() to avoid confusion with the watchdog subsystem and to be consistent with the existing name lockup_detector_init(). Also provide comment blocks to explain the watchdog_running and watchdog_suspended variables and their relationship. Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Stephane Eranian <eranian@google.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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999bbe49 |
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04-Sep-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: use suspend/resume interface in fixup_ht_bug() Remove watchdog_nmi_disable_all() and watchdog_nmi_enable_all() since these functions are no longer needed. If a subsystem has a need to deactivate the watchdog temporarily, it should utilize the watchdog_suspend() and watchdog_resume() functions. [akpm@linux-foundation.org: fix build with CONFIG_LOCKUP_DETECTOR=m] Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Stephane Eranian <eranian@google.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8c073d27 |
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04-Sep-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: introduce watchdog_suspend() and watchdog_resume() This interface can be utilized to deactivate the hard and soft lockup detector temporarily. Callers are expected to minimize the duration of deactivation. Multiple deactivations are allowed to occur in parallel but should be rare in practice. [akpm@linux-foundation.org: remove unneeded static initialization] Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Stephane Eranian <eranian@google.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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aacfbe6a |
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04-Sep-2015 |
Guenter Roeck <linux@roeck-us.net> |
kernel/watchdog: move NMI function header declarations from watchdog.h to nmi.h The kernel's NMI watchdog has nothing to do with the watchdog subsystem. Its header declarations should be in linux/nmi.h, not linux/watchdog.h. The code provided two sets of dummy functions if HARDLOCKUP_DETECTOR is not configured, one in the include file and one in kernel/watchdog.c. Remove the dummy functions from kernel/watchdog.c and use those from the include file. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Cc: Stephane Eranian <eranian@google.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Don Zickus <dzickus@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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b2c0b2cb |
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03-Sep-2014 |
Russell King <rmk+kernel@arm.linux.org.uk> |
nmi: create generic NMI backtrace implementation x86s NMI backtrace implementation (for arch_trigger_all_cpu_backtrace()) is fairly generic in nature - the only architecture specific bits are the act of raising the NMI to other CPUs, and reporting the status of the NMI handler. These are fairly simple to factor out, and produce a generic implementation which can be shared between ARM and x86. Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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fe4ba3c3 |
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24-Jun-2015 |
Chris Metcalf <cmetcalf@ezchip.com> |
watchdog: add watchdog_cpumask sysctl to assist nohz Change the default behavior of watchdog so it only runs on the housekeeping cores when nohz_full is enabled at build and boot time. Allow modifying the set of cores the watchdog is currently running on with a new kernel.watchdog_cpumask sysctl. In the current system, the watchdog subsystem runs a periodic timer that schedules the watchdog kthread to run. However, nohz_full cores are designed to allow userspace application code running on those cores to have 100% access to the CPU. So the watchdog system prevents the nohz_full application code from being able to run the way it wants to, thus the motivation to suppress the watchdog on nohz_full cores, which this patchset provides by default. However, if we disable the watchdog globally, then the housekeeping cores can't benefit from the watchdog functionality. So we allow disabling it only on some cores. See Documentation/lockup-watchdogs.txt for more information. [jhubbard@nvidia.com: fix a watchdog crash in some configurations] Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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692297d8 |
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14-Apr-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: introduce the hardlockup_detector_disable() function Have kvm_guest_init() use hardlockup_detector_disable() instead of watchdog_enable_hardlockup_detector(false). Remove the watchdog_hardlockup_detector_is_enabled() and the watchdog_enable_hardlockup_detector() function which are no longer needed. Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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195daf66 |
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14-Apr-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: enable the new user interface of the watchdog mechanism With the current user interface of the watchdog mechanism it is only possible to disable or enable both lockup detectors at the same time. This series introduces new kernel parameters and changes the semantics of some existing kernel parameters, so that the hard lockup detector and the soft lockup detector can be disabled or enabled individually. With this series applied, the user interface is as follows. - parameters in /proc/sys/kernel . soft_watchdog This is a new parameter to control and examine the run state of the soft lockup detector. . nmi_watchdog The semantics of this parameter have changed. It can now be used to control and examine the run state of the hard lockup detector. . watchdog This parameter is still available to control the run state of both lockup detectors at the same time. If this parameter is examined, it shows the logical OR of soft_watchdog and nmi_watchdog. . watchdog_thresh The semantics of this parameter are not affected by the patch. - kernel command line parameters . nosoftlockup The semantics of this parameter have changed. It can now be used to disable the soft lockup detector at boot time. . nmi_watchdog=0 or nmi_watchdog=1 Disable or enable the hard lockup detector at boot time. The patch introduces '=1' as a new option. . nowatchdog The semantics of this parameter are not affected by the patch. It is still available to disable both lockup detectors at boot time. Also, remove the proc_dowatchdog() function which is no longer needed. [dzickus@redhat.com: wrote changelog] [dzickus@redhat.com: update documentation for kernel params and sysctl] Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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83a80a39 |
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14-Apr-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: introduce separate handlers for parameters in /proc/sys/kernel Separate handlers for each watchdog parameter in /proc/sys/kernel replace the proc_dowatchdog() function. Three of those handlers merely call proc_watchdog_common() with one different argument. Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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84d56e66 |
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14-Apr-2015 |
Ulrich Obergfell <uobergfe@redhat.com> |
watchdog: new definitions and variables, initialization The hardlockup and softockup had always been tied together. Due to the request of KVM folks, they had a need to have one enabled but not the other. Internally rework the code to split things apart more cleanly. There is a bunch of churn here, but the end result should be code that should be easier to maintain and fix without knowing the internals of what is going on. This patch (of 9): Introduce new definitions and variables to separate the user interface in /proc/sys/kernel from the internal run state of the lockup detectors. The internal run state is represented by two bits in a new variable that is named 'watchdog_enabled'. This helps simplify the code, for example: - In order to check if any of the two lockup detectors is enabled, it is sufficient to check if 'watchdog_enabled' is not zero. - In order to enable/disable one or both lockup detectors, it is sufficient to set/clear one or both bits in 'watchdog_enabled'. - Concurrent updates of 'watchdog_enabled' need not be synchronized via a spinlock or a mutex. Updates can either be atomic or concurrency can be detected by using 'cmpxchg'. Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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6e7458a6 |
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13-Oct-2014 |
Ulrich Obergfell <uobergfe@redhat.com> |
kernel/watchdog.c: control hard lockup detection default In some cases we don't want hard lockup detection enabled by default. An example is when running as a guest. Introduce watchdog_enable_hardlockup_detector(bool) allowing those cases to disable hard lockup detection. This must be executed early by the boot processor from e.g. smp_prepare_boot_cpu, in order to allow kernel command line arguments to override it, as well as to avoid hard lockup detection being enabled before we've had a chance to indicate that it's unwanted. In summary, initial boot: default=enabled smp_prepare_boot_cpu watchdog_enable_hardlockup_detector(false): default=disabled cmdline has 'nmi_watchdog=1': default=enabled The running kernel still has the ability to enable/disable at any time with /proc/sys/kernel/nmi_watchdog us usual. However even when the default has been overridden /proc/sys/kernel/nmi_watchdog will initially show '1'. To truly turn it on one must disable/enable it, i.e. echo 0 > /proc/sys/kernel/nmi_watchdog echo 1 > /proc/sys/kernel/nmi_watchdog This patch will be immediately useful for KVM with the next patch of this series. Other hypervisor guest types may find it useful as well. [akpm@linux-foundation.org: fix build] [dzickus@redhat.com: fix compile issues on sparc] Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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44a69f61 |
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22-Jul-2014 |
Tomasz Nowicki <tomasz.nowicki@linaro.org> |
acpi, apei, ghes: Make NMI error notification to be GHES architecture extension. Currently APEI depends on x86 architecture. It is because of NMI hardware error notification of GHES which is currently supported by x86 only. However, many other APEI features can be still used perfectly by other architectures. This commit adds two symbols: 1. HAVE_ACPI_APEI for those archs which support APEI. 2. HAVE_ACPI_APEI_NMI which is used for NMI code isolation in ghes.c file. NMI related data and functions are grouped so they can be wrapped inside one #ifdef section. Appropriate function stubs are provided for !NMI case. Note there is no functional changes for x86 due to hard selected HAVE_ACPI_APEI and HAVE_ACPI_APEI_NMI symbols. Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org> Acked-by: Borislav Petkov <bp@suse.de> Signed-off-by: Tony Luck <tony.luck@intel.com>
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ed235875 |
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23-Jun-2014 |
Aaron Tomlin <atomlin@redhat.com> |
kernel/watchdog.c: print traces for all cpus on lockup detection A 'softlockup' is defined as a bug that causes the kernel to loop in kernel mode for more than a predefined period to time, without giving other tasks a chance to run. Currently, upon detection of this condition by the per-cpu watchdog task, debug information (including a stack trace) is sent to the system log. On some occasions, we have observed that the "victim" rather than the actual "culprit" (i.e. the owner/holder of the contended resource) is reported to the user. Often this information has proven to be insufficient to assist debugging efforts. To avoid loss of useful debug information, for architectures which support NMI, this patch makes it possible to improve soft lockup reporting. This is accomplished by issuing an NMI to each cpu to obtain a stack trace. If NMI is not supported we just revert back to the old method. A sysctl and boot-time parameter is available to toggle this feature. [dzickus@redhat.com: add CONFIG_SMP in certain areas] [akpm@linux-foundation.org: additional CONFIG_SMP=n optimisations] [mq@suse.cz: fix warning] Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Jan Moskyto Matejka <mq@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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f3aca3d0 |
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23-Jun-2014 |
Aaron Tomlin <atomlin@redhat.com> |
nmi: provide the option to issue an NMI back trace to every cpu but current Sometimes it is preferred not to use the trigger_all_cpu_backtrace() routine when one wants to avoid capturing a back trace for current. For instance if one was previously captured recently. This patch provides a new routine namely trigger_allbutself_cpu_backtrace() which offers the flexibility to issue an NMI to every cpu but current and capture a back trace accordingly. Patch x86 and sparc to support new routine. [dzickus@redhat.com: add stub in #else clause] [dzickus@redhat.com: don't print message in single processor case, wrap with get/put_cpu based on Oleg's suggestion] [sfr@canb.auug.org.au: undo C99ism] Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Acked-by: David S. Miller <davem@davemloft.net> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3c00ea82 |
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19-May-2013 |
Frederic Weisbecker <fweisbec@gmail.com> |
watchdog: Rename confusing state variable We have two very conflicting state variable names in the watchdog: * watchdog_enabled: This one reflects the user interface. It's set to 1 by default and can be overriden with boot options or sysctl/procfs interface. * watchdog_disabled: This is the internal toggle state that tells if watchdog threads, timers and NMI events are currently running or not. This state mostly depends on the user settings. It's a convenient state latch. Now we really need to find clearer names because those are just too confusing to encourage deep review. watchdog_enabled now becomes watchdog_user_enabled to reflect its purpose as an interface. watchdog_disabled becomes watchdog_running to suggest its role as a pure internal state. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Cc: Anish Singh <anish198519851985@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Don Zickus <dzickus@redhat.com>
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d314d74c |
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23-Mar-2012 |
Cong Wang <xiyou.wangcong@gmail.com> |
nmi watchdog: do not use cpp symbol in Kconfig ARCH_HAS_NMI_WATCHDOG is a macro defined by arch, but config HARDLOCKUP_DETECTOR depends on it. This is wrong, ARCH_HAS_NMI_WATCHDOG has to be a Kconfig config, and arch's need it should select it explicitly. Signed-off-by: WANG Cong <xiyou.wangcong@gmail.com> Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Mike Frysinger <vapier@gentoo.org> Cc: David Howells <dhowells@redhat.com> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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4eec42f3 |
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22-May-2011 |
Mandeep Singh Baines <msb@chromium.org> |
watchdog: Change the default timeout and configure nmi watchdog period based on watchdog_thresh Before the conversion of the NMI watchdog to perf event, the watchdog timeout was 5 seconds. Now it is 60 seconds. For my particular application, netbooks, 5 seconds was a better timeout. With a short timeout, we catch faults earlier and are able to send back a panic. With a 60 second timeout, the user is unlikely to wait and will instead hit the power button, causing us to lose the panic info. This change configures the NMI period to watchdog_thresh and sets the softlockup_thresh to watchdog_thresh * 2. In addition, watchdog_thresh was reduced to 10 seconds as suggested by Ingo Molnar. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1306127423-3347-4-git-send-email-msb@chromium.org Signed-off-by: Ingo Molnar <mingo@elte.hu> LKML-Reference: <20110517071642.GF22305@elte.hu>
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586692a5 |
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22-May-2011 |
Mandeep Singh Baines <msb@chromium.org> |
watchdog: Disable watchdog when thresh is zero This restores the previous behavior of softlock_thresh. Currently, setting watchdog_thresh to zero causes the watchdog kthreads to consume a lot of CPU. In addition, the logic of proc_dowatchdog_thresh and proc_dowatchdog_enabled has been factored into proc_dowatchdog. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Cc: Marcin Slusarz <marcin.slusarz@gmail.com> Cc: Don Zickus <dzickus@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/1306127423-3347-3-git-send-email-msb@chromium.org Signed-off-by: Ingo Molnar <mingo@elte.hu> LKML-Reference: <20110517071018.GE22305@elte.hu>
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4a7863cc |
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22-Dec-2010 |
Don Zickus <dzickus@redhat.com> |
x86, nmi_watchdog: Remove ARCH_HAS_NMI_WATCHDOG and rely on CONFIG_HARDLOCKUP_DETECTOR The x86 arch has shifted its use of the nmi_watchdog from a local implementation to the global one provide by kernel/watchdog.c. This shift has caused a whole bunch of compile problems under different config options. I attempt to simplify things with the patch below. In order to simplify things, I had to come to terms with the meaning of two terms ARCH_HAS_NMI_WATCHDOG and CONFIG_HARDLOCKUP_DETECTOR. Basically they mean the same thing, the former on a local level and the latter on a global level. With the old x86 nmi watchdog gone, there is no need to rely on defining the ARCH_HAS_NMI_WATCHDOG variable because it doesn't make sense any more. x86 will now use the global implementation. The changes below do a few things. First it changes the few places that relied on ARCH_HAS_NMI_WATCHDOG to use CONFIG_X86_LOCAL_APIC (the former was an alias for the latter anyway, so nothing unusual here). Those pieces of code were relying more on local apic functionality the nmi watchdog functionality, so the change should make sense. Second, I removed the x86 implementation of touch_nmi_watchdog(). It isn't need now, instead x86 will rely on kernel/watchdog.c's implementation. Third, I removed the #define ARCH_HAS_NMI_WATCHDOG itself from x86. And tweaked the include/linux/nmi.h file to tell users to look for an externally defined touch_nmi_watchdog in the case of ARCH_HAS_NMI_WATCHDOG _or_ CONFIG_HARDLOCKUP_DETECTOR. This changes removes some of the ugliness in that file. Finally, I added a Kconfig dependency for CONFIG_HARDLOCKUP_DETECTOR that said you can't have ARCH_HAS_NMI_WATCHDOG _and_ CONFIG_HARDLOCKUP_DETECTOR. You can only have one nmi_watchdog. Tested with ARCH=i386: allnoconfig, defconfig, allyesconfig, (various broken configs) ARCH=x86_64: allnoconfig, defconfig, allyesconfig, (various broken configs) Hopefully, after this patch I won't get any more compile broken emails. :-) v3: changed a couple of 'linux/nmi.h' -> 'asm/nmi.h' to pick-up correct function prototypes when CONFIG_HARDLOCKUP_DETECTOR is not set. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: fweisbec@gmail.com LKML-Reference: <1293044403-14117-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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96a84c20 |
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29-Nov-2010 |
Don Zickus <dzickus@redhat.com> |
lockup detector: Compile fixes from removing the old x86 nmi watchdog My patch that removed the old x86 nmi watchdog broke other arches. This change reverts a piece of that patch and puts the change in the correct spot. Signed-off-by: Don Zickus <dzickus@redhat.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Cc: fweisbec@gmail.com Cc: yinghai@kernel.org LKML-Reference: <1291068437-5331-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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072b198a |
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12-Nov-2010 |
Don Zickus <dzickus@redhat.com> |
x86, nmi_watchdog: Remove all stub function calls from old nmi_watchdog Now that the bulk of the old nmi_watchdog is gone, remove all the stub variables and hooks associated with it. This touches lots of files mainly because of how the io_apic nmi_watchdog was implemented. Now that the io_apic nmi_watchdog is forever gone, remove all its fingers. Most of this code was not being exercised by virtue of nmi_watchdog != NMI_IO_APIC, so there shouldn't be anything to risky here. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: fweisbec@gmail.com Cc: gorcunov@openvz.org LKML-Reference: <1289578944-28564-3-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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5f2b0ba4 |
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12-Nov-2010 |
Don Zickus <dzickus@redhat.com> |
x86, nmi_watchdog: Remove the old nmi_watchdog Now that we have a new nmi_watchdog that is more generic and sits on top of the perf subsystem, we really do not need the old nmi_watchdog any more. In addition, the old nmi_watchdog doesn't really work if you are using the default clocksource, hpet. The old nmi_watchdog code relied on local apic interrupts to determine if the cpu is still alive. With hpet as the clocksource, these interrupts don't increment any more and the old nmi_watchdog triggers false postives. This piece removes the old nmi_watchdog code and stubs out any variables and functions calls. The stubs are the same ones used by the new nmi_watchdog code, so it should be well tested. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: fweisbec@gmail.com Cc: gorcunov@openvz.org LKML-Reference: <1289578944-28564-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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cafcd80d |
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14-May-2010 |
Don Zickus <dzickus@redhat.com> |
lockup_detector: Cross arch compile fixes Combining the softlockup and hardlockup code causes watchdog.c to build even without the hardlockup detection support. So if an arch, that has the previous and the new nmi watchdog implementations cohabiting, wants to know if the generic one is in use, CONFIG_LOCKUP_DETECTOR is not a reliable check. We need to use CONFIG_HARDLOCKUP_DETECTOR instead. Fixes: kernel/built-in.o: In function `touch_nmi_watchdog': (.text+0x449bc): multiple definition of `touch_nmi_watchdog' arch/sparc/kernel/built-in.o:(.text+0x11b28): first defined here Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Don Zickus <dzickus@redhat.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> LKML-Reference: <20100514151121.GR15159@redhat.com> [ use CONFIG_HARDLOCKUP_DETECTOR instead of CONFIG_PERF_EVENTS_NMI] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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58687acb |
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07-May-2010 |
Don Zickus <dzickus@redhat.com> |
lockup_detector: Combine nmi_watchdog and softlockup detector The new nmi_watchdog (which uses the perf event subsystem) is very similar in structure to the softlockup detector. Using Ingo's suggestion, I combined the two functionalities into one file: kernel/watchdog.c. Now both the nmi_watchdog (or hardlockup detector) and softlockup detector sit on top of the perf event subsystem, which is run every 60 seconds or so to see if there are any lockups. To detect hardlockups, cpus not responding to interrupts, I implemented an hrtimer that runs 5 times for every perf event overflow event. If that stops counting on a cpu, then the cpu is most likely in trouble. To detect softlockups, tasks not yielding to the scheduler, I used the previous kthread idea that now gets kicked every time the hrtimer fires. If the kthread isn't being scheduled neither is anyone else and the warning is printed to the console. I tested this on x86_64 and both the softlockup and hardlockup paths work. V2: - cleaned up the Kconfig and softlockup combination - surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI - seperated out the softlockup case from perf event subsystem - re-arranged the enabling/disabling nmi watchdog from proc space - added cpumasks for hardlockup failure cases - removed fallback to soft events if no PMU exists for hard events V3: - comment cleanups - drop support for older softlockup code - per_cpu cleanups - completely remove software clock base hardlockup detector - use per_cpu masking on hard/soft lockup detection - #ifdef cleanups - rename config option NMI_WATCHDOG to LOCKUP_DETECTOR - documentation additions V4: - documentation fixes - convert per_cpu to __get_cpu_var - powerpc compile fixes V5: - split apart warn flags for hard and soft lockups TODO: - figure out how to make an arch-agnostic clock2cycles call (if possible) to feed into perf events as a sample period [fweisbec: merged conflict patch] Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Eric Paris <eparis@redhat.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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47195d57 |
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22-Feb-2010 |
Don Zickus <dzickus@redhat.com> |
nmi_watchdog: Clean up various small details Mostly copy/paste whitespace damage with a couple of nitpicks by the checkpatch script. Fix the struct definition as requested by Ingo too. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: peterz@infradead.org Cc: gorcunov@gmail.com Cc: aris@redhat.com LKML-Reference: <1266880143-24943-1-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> -- arch/x86/kernel/apic/hw_nmi.c | 14 +++++------ arch/x86/kernel/traps.c | 6 ++-- include/linux/nmi.h | 2 - kernel/nmi_watchdog.c | 51 ++++++++++++++++++++---------------------- 4 files changed, 36 insertions(+), 37 deletions(-)
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504d7cf1 |
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12-Feb-2010 |
Don Zickus <dzickus@redhat.com> |
nmi_watchdog: Compile and portability fixes The original patch was x86_64 centric. Changed the code to make it less so. ested by building and running on a powerpc. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: peterz@infradead.org Cc: gorcunov@gmail.com Cc: aris@redhat.com LKML-Reference: <1266013161-31197-2-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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84e478c6 |
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05-Feb-2010 |
Don Zickus <dzickus@redhat.com> |
nmi_watchdog: Config option to enable new nmi_watchdog These are the bits that enable the new nmi_watchdog and safely isolate the old nmi_watchdog. Only one or the other can run, not both at the same time. Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: gorcunov@gmail.com Cc: aris@redhat.com Cc: peterz@infradead.org LKML-Reference: <1265424425-31562-4-git-send-email-dzickus@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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47cab6a7 |
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03-Aug-2009 |
Ingo Molnar <mingo@elte.hu> |
debug lockups: Improve lockup detection, fix generic arch fallback As Andrew noted, my previous patch ("debug lockups: Improve lockup detection") broke/removed SysRq-L support from architecture that do not provide a __trigger_all_cpu_backtrace implementation. Restore a fallback path and clean up the SysRq-L machinery a bit: - Rename the arch method to arch_trigger_all_cpu_backtrace() - Simplify the define - Document the method a bit - in the hope of more architectures adding support for it. [ The patch touches Sparc code for the rename. ] Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "David S. Miller" <davem@davemloft.net> LKML-Reference: <20090802140809.7ec4bb6b.akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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5d0e600d |
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13-Feb-2007 |
Ingo Molnar <mingo@elte.hu> |
[PATCH] x86: fix laptop bootup hang in init_acpi() During kernel bootup, a new T60 laptop (CoreDuo, 32-bit) hangs about 10%-20% of the time in acpi_init(): Calling initcall 0xc055ce1a: topology_init+0x0/0x2f() Calling initcall 0xc055d75e: mtrr_init_finialize+0x0/0x2c() Calling initcall 0xc05664f3: param_sysfs_init+0x0/0x175() Calling initcall 0xc014cb65: pm_sysrq_init+0x0/0x17() Calling initcall 0xc0569f99: init_bio+0x0/0xf4() Calling initcall 0xc056b865: genhd_device_init+0x0/0x50() Calling initcall 0xc056c4bd: fbmem_init+0x0/0x87() Calling initcall 0xc056dd74: acpi_init+0x0/0x1ee() It's a hard hang that not even an NMI could punch through! Frustratingly, adding printks or function tracing to the ACPI code made the hangs go away ... After some time an additional detail emerged: disabling the NMI watchdog made these occasional hangs go away. So i spent the better part of today trying to debug this and trying out various theories when i finally found the likely reason for the hang: if acpi_ns_initialize_devices() executes an _INI AML method and an NMI happens to hit that AML execution in the wrong moment, the machine would hang. (my theory is that this must be some sort of chipset setup method doing stores to chipset mmio registers?) Unfortunately given the characteristics of the hang it was sheer impossible to figure out which of the numerous AML methods is impacted by this problem. As a workaround i wrote an interface to disable chipset-based NMIs while executing _INI sections - and indeed this fixed the hang. I did a boot-loop of 100 separate reboots and none hung - while without the patch it would hang every 5-10 attempts. Out of caution i did not touch the nmi_watchdog=2 case (it's not related to the chipset anyway and didnt hang). I implemented this for both x86_64 and i686, tested the i686 laptop both with nmi_watchdog=1 [which triggered the hangs] and nmi_watchdog=2, and tested an Athlon64 box with the 64-bit kernel as well. Everything builds and works with the patch applied. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Andi Kleen <ak@suse.de> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bb81a09e |
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06-Dec-2006 |
Andrew Morton <akpm@osdl.org> |
[PATCH] x86: all cpu backtrace When a spinlock lockup occurs, arrange for the NMI code to emit an all-cpu backtrace, so we get to see which CPU is holding the lock, and where. Cc: Andi Kleen <ak@muc.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Andi Kleen <ak@suse.de>
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9938406a |
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29-Sep-2006 |
Michal Schmidt <xschmi00@stud.feec.vutbr.cz> |
[PATCH] Make touch_nmi_watchdog imply touch_softlockup_watchdog on all archs touch_nmi_watchdog() calls touch_softlockup_watchdog() on both architectures that implement it (i386 and x86_64). On other architectures it does nothing at all. touch_nmi_watchdog() should imply touch_softlockup_watchdog() on all architectures. Suggested by Andi Kleen. [heiko.carstens@de.ibm.com: s390 fix] Signed-off-by: Michal Schmidt <xschmi00@stud.feec.vutbr.cz> Cc: Andi Kleen <ak@muc.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michal Schmidt <xschmi00@stud.feec.vutbr.cz> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1da177e4 |
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16-Apr-2005 |
Linus Torvalds <torvalds@ppc970.osdl.org> |
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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