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H A D | sysctl.h | diff 3bc269cf Tue Aug 08 16:49:59 MDT 2023 Joel Granados <joel.granados@gmail.com> sysctl: Add size arg to __register_sysctl_init This commit adds table_size to __register_sysctl_init in preparation for the removal of the sentinel elements in the ctl_table arrays (last empty markers). And though we do *not* remove any sentinels in this commit, we set things up by calculating the ctl_table array size with ARRAY_SIZE. We add a table_size argument to __register_sysctl_init and modify the register_sysctl_init macro to calculate the array size with ARRAY_SIZE. The original callers do not need to be updated as they will go through the new macro. Signed-off-by: Joel Granados <j.granados@samsung.com> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> diff 6213834c Tue Jun 28 03:22:33 MDT 2022 Muchun Song <songmuchun@bytedance.com> mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability There is a discussion about the name of hugetlb_vmemmap_alloc/free in thread [1]. The suggestion suggested by David is rename "alloc/free" to "optimize/restore" to make functionalities clearer to users, "optimize" means the function will optimize vmemmap pages, while "restore" means restoring its vmemmap pages discared before. This commit does this. Another discussion is the confusion RESERVE_VMEMMAP_NR isn't used explicitly for vmemmap_addr but implicitly for vmemmap_end in hugetlb_vmemmap_alloc/free. David suggested we can compute what hugetlb_vmemmap_init() does now at runtime. We do not need to worry for the overhead of computing at runtime since the calculation is simple enough and those functions are not in a hot path. This commit has the following improvements: 1) The function suffixed name ("optimize/restore") is more expressive. 2) The logic becomes less weird in hugetlb_vmemmap_optimize/restore(). 3) The hugetlb_vmemmap_init() does not need to be exported anymore. 4) A ->optimize_vmemmap_pages field in struct hstate is killed. 5) There is only one place where checks is_power_of_2(sizeof(struct page)) instead of two places. 6) Add more comments for hugetlb_vmemmap_optimize/restore(). 7) For external users, hugetlb_optimize_vmemmap_pages() is used for detecting if the HugeTLB's vmemmap pages is optimizable originally. In this commit, it is killed and we introduce a new helper hugetlb_vmemmap_optimizable() to replace it. The name is more expressive. Link: https://lore.kernel.org/all/20220404074652.68024-2-songmuchun@bytedance.com/ [1] Link: https://lkml.kernel.org/r/20220628092235.91270-7-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Oscar Salvador <osalvador@suse.de> Cc: Will Deacon <will@kernel.org> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 5475e8f0 Fri Jan 21 23:12:18 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> random: move the random sysctl declarations to its own file kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the random sysctls to their own file and use register_sysctl_init(). [mcgrof@kernel.org: commit log update to justify the move] Link: https://lkml.kernel.org/r/20211124231435.1445213-3-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Joel Becker <jlbec@evilplan.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Kees Cook <keescook@chromium.org> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Qing Wang <wangqing@vivo.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 6aad36d4 Fri Jan 21 23:12:13 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> firmware_loader: move firmware sysctl to its own files Patch series "sysctl: 3rd set of kernel/sysctl cleanups", v2. This is the third set of patches to help address cleaning the kitchen seink in kernel/sysctl.c and to move sysctls away to where they are actually implemented / used. This patch (of 8): kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the firmware configuration sysctl table to the only place where it is used, and make it clear that if sysctls are disabled this is not used. [akpm@linux-foundation.org: export register_firmware_config_sysctl and unregister_firmware_config_sysctl to modules] [akpm@linux-foundation.org: use EXPORT_SYMBOL_NS_GPL instead] [sfr@canb.auug.org.au: fix that so it compiles] Link: https://lkml.kernel.org/r/20211201160626.401d828d@canb.auug.org.au [mcgrof@kernel.org: major commit log update to justify the move] Link: https://lkml.kernel.org/r/20211124231435.1445213-1-mcgrof@kernel.org Link: https://lkml.kernel.org/r/20211124231435.1445213-2-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Stephen Kitt <steve@sk2.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: John Ogness <john.ogness@linutronix.de> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Antti Palosaari <crope@iki.fi> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Mark Fasheh <mark@fasheh.com> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Qing Wang <wangqing@vivo.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 78e36f3b Fri Jan 21 23:10:55 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> sysctl: move some boundary constants from sysctl.c to sysctl_vals sysctl has helpers which let us specify boundary values for a min or max int value. Since these are used for a boundary check only they don't change, so move these variables to sysctl_vals to avoid adding duplicate variables. This will help with our cleanup of kernel/sysctl.c. [akpm@linux-foundation.org: update it for "mm/pagealloc: sysctl: change watermark_scale_factor max limit to 30%"] [mcgrof@kernel.org: major rebase] Link: https://lkml.kernel.org/r/20211123202347.818157-3-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Qing Wang <wangqing@vivo.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3ddd9a80 Fri Jan 21 23:10:50 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> sysctl: add a new register_sysctl_init() interface Patch series "sysctl: first set of kernel/sysctl cleanups", v2. Finally had time to respin the series of the work we had started last year on cleaning up the kernel/sysct.c kitchen sink. People keeps stuffing their sysctls in that file and this creates a maintenance burden. So this effort is aimed at placing sysctls where they actually belong. I'm going to split patches up into series as there is quite a bit of work. This first set adds register_sysctl_init() for uses of registerting a sysctl on the init path, adds const where missing to a few places, generalizes common values so to be more easy to share, and starts the move of a few kernel/sysctl.c out where they belong. The majority of rework on v2 in this first patch set is 0-day fixes. Eric Biederman's feedback is later addressed in subsequent patch sets. I'll only post the first two patch sets for now. We can address the rest once the first two patch sets get completely reviewed / Acked. This patch (of 9): The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. Today though folks heavily rely on tables on kernel/sysctl.c so they can easily just extend this table with their needed sysctls. In order to help users move their sysctls out we need to provide a helper which can be used during code initialization. We special-case the initialization use of register_sysctl() since it *is* safe to fail, given all that sysctls do is provide a dynamic interface to query or modify at runtime an existing variable. So the use case of register_sysctl() on init should *not* stop if the sysctls don't end up getting registered. It would be counter productive to stop boot if a simple sysctl registration failed. Provide a helper for init then, and document the recommended init levels to use for callers of this routine. We will later use this in subsequent patches to start slimming down kernel/sysctl.c tables and moving sysctl registration to the code which actually needs these sysctls. [mcgrof@kernel.org: major commit log and documentation rephrasing also moved to fs/proc/proc_sysctl.c ] Link: https://lkml.kernel.org/r/20211123202347.818157-1-mcgrof@kernel.org Link: https://lkml.kernel.org/r/20211123202347.818157-2-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Paul Turner <pjt@google.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Qing Wang <wangqing@vivo.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jan Kara <jack@suse.cz> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Stephen Kitt <steve@sk2.org> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
/linux-master/fs/proc/ | ||
H A D | proc_sysctl.c | diff 3bc269cf Tue Aug 08 16:49:59 MDT 2023 Joel Granados <joel.granados@gmail.com> sysctl: Add size arg to __register_sysctl_init This commit adds table_size to __register_sysctl_init in preparation for the removal of the sentinel elements in the ctl_table arrays (last empty markers). And though we do *not* remove any sentinels in this commit, we set things up by calculating the ctl_table array size with ARRAY_SIZE. We add a table_size argument to __register_sysctl_init and modify the register_sysctl_init macro to calculate the array size with ARRAY_SIZE. The original callers do not need to be updated as they will go through the new macro. Signed-off-by: Joel Granados <j.granados@samsung.com> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> diff f1aa2eb5 Fri Feb 10 07:58:23 MST 2023 Ondrej Mosnacek <omosnace@redhat.com> sysctl: fix proc_dobool() usability Currently proc_dobool expects a (bool *) in table->data, but sizeof(int) in table->maxsize, because it uses do_proc_dointvec() directly. This is unsafe for at least two reasons: 1. A sysctl table definition may use { .data = &variable, .maxsize = sizeof(variable) }, not realizing that this makes the sysctl unusable (see the Fixes: tag) and that they need to use the completely counterintuitive sizeof(int) instead. 2. proc_dobool() will currently try to parse an array of values if given .maxsize >= 2*sizeof(int), but will try to write values of type bool by offsets of sizeof(int), so it will not work correctly with neither an (int *) nor a (bool *). There is no .maxsize validation to prevent this. Fix this by: 1. Constraining proc_dobool() to allow only one value and .maxsize == sizeof(bool). 2. Wrapping the original struct ctl_table in a temporary one with .data pointing to a local int variable and .maxsize set to sizeof(int) and passing this one to proc_dointvec(), converting the value to/from bool as needed (using proc_dou8vec_minmax() as an example). 3. Extending sysctl_check_table() to enforce proc_dobool() expectations. 4. Fixing the proc_dobool() docstring (it was just copy-pasted from proc_douintvec, apparently...). 5. Converting all existing proc_dobool() users to set .maxsize to sizeof(bool) instead of sizeof(int). Fixes: 83efeeeb3d04 ("tty: Allow TIOCSTI to be disabled") Fixes: a2071573d634 ("sysctl: introduce new proc handler proc_dobool") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> diff 78e36f3b Fri Jan 21 23:10:55 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> sysctl: move some boundary constants from sysctl.c to sysctl_vals sysctl has helpers which let us specify boundary values for a min or max int value. Since these are used for a boundary check only they don't change, so move these variables to sysctl_vals to avoid adding duplicate variables. This will help with our cleanup of kernel/sysctl.c. [akpm@linux-foundation.org: update it for "mm/pagealloc: sysctl: change watermark_scale_factor max limit to 30%"] [mcgrof@kernel.org: major rebase] Link: https://lkml.kernel.org/r/20211123202347.818157-3-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Paul Turner <pjt@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Qing Wang <wangqing@vivo.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Stephen Kitt <steve@sk2.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3ddd9a80 Fri Jan 21 23:10:50 MST 2022 Xiaoming Ni <nixiaoming@huawei.com> sysctl: add a new register_sysctl_init() interface Patch series "sysctl: first set of kernel/sysctl cleanups", v2. Finally had time to respin the series of the work we had started last year on cleaning up the kernel/sysct.c kitchen sink. People keeps stuffing their sysctls in that file and this creates a maintenance burden. So this effort is aimed at placing sysctls where they actually belong. I'm going to split patches up into series as there is quite a bit of work. This first set adds register_sysctl_init() for uses of registerting a sysctl on the init path, adds const where missing to a few places, generalizes common values so to be more easy to share, and starts the move of a few kernel/sysctl.c out where they belong. The majority of rework on v2 in this first patch set is 0-day fixes. Eric Biederman's feedback is later addressed in subsequent patch sets. I'll only post the first two patch sets for now. We can address the rest once the first two patch sets get completely reviewed / Acked. This patch (of 9): The kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. Today though folks heavily rely on tables on kernel/sysctl.c so they can easily just extend this table with their needed sysctls. In order to help users move their sysctls out we need to provide a helper which can be used during code initialization. We special-case the initialization use of register_sysctl() since it *is* safe to fail, given all that sysctls do is provide a dynamic interface to query or modify at runtime an existing variable. So the use case of register_sysctl() on init should *not* stop if the sysctls don't end up getting registered. It would be counter productive to stop boot if a simple sysctl registration failed. Provide a helper for init then, and document the recommended init levels to use for callers of this routine. We will later use this in subsequent patches to start slimming down kernel/sysctl.c tables and moving sysctl registration to the code which actually needs these sysctls. [mcgrof@kernel.org: major commit log and documentation rephrasing also moved to fs/proc/proc_sysctl.c ] Link: https://lkml.kernel.org/r/20211123202347.818157-1-mcgrof@kernel.org Link: https://lkml.kernel.org/r/20211123202347.818157-2-mcgrof@kernel.org Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Paul Turner <pjt@google.com> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Sebastian Reichel <sre@kernel.org> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Qing Wang <wangqing@vivo.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Jan Kara <jack@suse.cz> Cc: Amir Goldstein <amir73il@gmail.com> Cc: Stephen Kitt <steve@sk2.org> Cc: Antti Palosaari <crope@iki.fi> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Clemens Ladisch <clemens@ladisch.de> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Julia Lawall <julia.lawall@inria.fr> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Mark Fasheh <mark@fasheh.com> Cc: Phillip Potter <phil@philpotter.co.uk> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Douglas Gilbert <dgilbert@interlog.com> Cc: James E.J. Bottomley <jejb@linux.ibm.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 697edcb0 Sat Jan 23 22:02:16 MST 2021 Xiaoming Ni <nixiaoming@huawei.com> proc_sysctl: fix oops caused by incorrect command parameters The process_sysctl_arg() does not check whether val is empty before invoking strlen(val). If the command line parameter () is incorrectly configured and val is empty, oops is triggered. For example: "hung_task_panic=1" is incorrectly written as "hung_task_panic", oops is triggered. The call stack is as follows: Kernel command line: .... hung_task_panic ...... Call trace: __pi_strlen+0x10/0x98 parse_args+0x278/0x344 do_sysctl_args+0x8c/0xfc kernel_init+0x5c/0xf4 ret_from_fork+0x10/0x30 To fix it, check whether "val" is empty when "phram" is a sysctl field. Error codes are returned in the failure branch, and error logs are generated by parse_args(). Link: https://lkml.kernel.org/r/20210118133029.28580-1-nixiaoming@huawei.com Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Heiner Kallweit <hkallweit1@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: <stable@vger.kernel.org> [5.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 0a477e1a Sun Jun 07 22:40:27 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support handling command line aliases We can now handle sysctl parameters on kernel command line, but historically some parameters introduced their own command line equivalent, which we don't want to remove for compatibility reasons. We can, however, convert them to the generic infrastructure with a table translating the legacy command line parameters to their sysctl names, and removing the one-off param handlers. This patch adds the support and makes the first conversion to demonstrate it, on the (deprecated) numa_zonelist_order parameter. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: David Rientjes <rientjes@google.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20200427180433.7029-3-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> diff 3db978d4 Sun Jun 07 22:40:24 MDT 2020 Vlastimil Babka <vbabka@suse.cz> kernel/sysctl: support setting sysctl parameters from kernel command line Patch series "support setting sysctl parameters from kernel command line", v3. This series adds support for something that seems like many people always wanted but nobody added it yet, so here's the ability to set sysctl parameters via kernel command line options in the form of sysctl.vm.something=1 The important part is Patch 1. The second, not so important part is an attempt to clean up legacy one-off parameters that do the same thing as a sysctl. I don't want to remove them completely for compatibility reasons, but with generic sysctl support the idea is to remove the one-off param handlers and treat the parameters as aliases for the sysctl variants. I have identified several parameters that mention sysctl counterparts in Documentation/admin-guide/kernel-parameters.txt but there might be more. The conversion also has varying level of success: - numa_zonelist_order is converted in Patch 2 together with adding the necessary infrastructure. It's easy as it doesn't really do anything but warn on deprecated value these days. - hung_task_panic is converted in Patch 3, but there's a downside that now it only accepts 0 and 1, while previously it was any integer value - nmi_watchdog maps to two sysctls nmi_watchdog and hardlockup_panic, so there's no straighforward conversion possible - traceoff_on_warning is a flag without value and it would be required to handle that somehow in the conversion infractructure, which seems pointless for a single flag This patch (of 5): A recently proposed patch to add vm_swappiness command line parameter in addition to existing sysctl [1] made me wonder why we don't have a general support for passing sysctl parameters via command line. Googling found only somebody else wondering the same [2], but I haven't found any prior discussion with reasons why not to do this. Settings the vm_swappiness issue aside (the underlying issue might be solved in a different way), quick search of kernel-parameters.txt shows there are already some that exist as both sysctl and kernel parameter - hung_task_panic, nmi_watchdog, numa_zonelist_order, traceoff_on_warning. A general mechanism would remove the need to add more of those one-offs and might be handy in situations where configuration by e.g. /etc/sysctl.d/ is impractical. Hence, this patch adds a new parse_args() pass that looks for parameters prefixed by 'sysctl.' and tries to interpret them as writes to the corresponding sys/ files using an temporary in-kernel procfs mount. This mechanism was suggested by Eric W. Biederman [3], as it handles all dynamically registered sysctl tables, even though we don't handle modular sysctls. Errors due to e.g. invalid parameter name or value are reported in the kernel log. The processing is hooked right before the init process is loaded, as some handlers might be more complicated than simple setters and might need some subsystems to be initialized. At the moment the init process can be started and eventually execute a process writing to /proc/sys/ then it should be also fine to do that from the kernel. Sysctls registered later on module load time are not set by this mechanism - it's expected that in such scenarios, setting sysctl values from userspace is practical enough. [1] https://lore.kernel.org/r/BL0PR02MB560167492CA4094C91589930E9FC0@BL0PR02MB5601.namprd02.prod.outlook.com/ [2] https://unix.stackexchange.com/questions/558802/how-to-set-sysctl-using-kernel-command-line-parameter [3] https://lore.kernel.org/r/87bloj2skm.fsf@x220.int.ebiederm.org/ Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: Ivan Teterevkov <ivan.teterevkov@nutanix.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: "Guilherme G . Piccoli" <gpiccoli@canonical.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christian Brauner <christian.brauner@ubuntu.com> Link: http://lkml.kernel.org/r/20200427180433.7029-1-vbabka@suse.cz Link: http://lkml.kernel.org/r/20200427180433.7029-2-vbabka@suse.cz Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
/linux-master/Documentation/admin-guide/ | ||
H A D | kernel-parameters.txt | diff 89ac522d Wed Feb 21 02:26:36 MST 2024 Maxime Ripard <mripard@kernel.org> drm/edid/firmware: Remove built-in EDIDs The EDID firmware loading mechanism introduced a few built-in EDIDs that could be forced on any connector, bypassing the EDIDs it exposes. While convenient, this limited set of EDIDs doesn't take into account the connector type, and we can end up with an EDID that is completely invalid for a given connector. For example, the edid/800x600.bin file matches the following EDID: edid-decode (hex): 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 05 16 01 03 6d 1b 14 78 ea 5e c0 a4 59 4a 98 25 20 50 54 01 00 00 45 40 01 01 01 01 01 01 01 01 01 01 01 01 01 01 a0 0f 20 00 31 58 1c 20 28 80 14 00 15 d0 10 00 00 1e 00 00 00 ff 00 4c 69 6e 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 3b 3d 24 26 05 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c 69 6e 75 78 20 53 56 47 41 0a 20 20 00 c2 ---------------- Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 27 cm x 20 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Standard Timings: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Detailed Timing Descriptors: DTD 1: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz (277 mm x 208 mm) Hfront 40 Hsync 128 Hback 88 Hpol P Vfront 1 Vsync 4 Vback 23 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 59-61 Hz V, 36-38 kHz H, max dotclock 50 MHz Display Product Name: 'Linux SVGA' Checksum: 0xc2 So, an analog monitor EDID. However, if the connector was an HDMI monitor for example, it breaks the HDMI specification that requires, among other things, a digital display, the VIC 1 mode and an HDMI Forum Vendor Specific Data Block in an CTA-861 extension. We thus end up with a completely invalid EDID, which thus might confuse HDMI-related code that could parse it. After some discussions on IRC, we identified mainly two ways to fix this: - We can either create more EDIDs for each connector type to provide a built-in EDID that matches the resolution passed in the name, and still be a sensible EDID for that connector type; - Or we can just prevent the EDID to be exposed to userspace if it's built-in. Or possibly both. However, the conclusion was that maybe we just don't need the built-in EDIDs at all and we should just get rid of them. So here we are. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Maxime Ripard <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240221092636.691701-1-mripard@kernel.org diff 89ac522d Wed Feb 21 02:26:36 MST 2024 Maxime Ripard <mripard@kernel.org> drm/edid/firmware: Remove built-in EDIDs The EDID firmware loading mechanism introduced a few built-in EDIDs that could be forced on any connector, bypassing the EDIDs it exposes. While convenient, this limited set of EDIDs doesn't take into account the connector type, and we can end up with an EDID that is completely invalid for a given connector. For example, the edid/800x600.bin file matches the following EDID: edid-decode (hex): 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 05 16 01 03 6d 1b 14 78 ea 5e c0 a4 59 4a 98 25 20 50 54 01 00 00 45 40 01 01 01 01 01 01 01 01 01 01 01 01 01 01 a0 0f 20 00 31 58 1c 20 28 80 14 00 15 d0 10 00 00 1e 00 00 00 ff 00 4c 69 6e 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 3b 3d 24 26 05 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c 69 6e 75 78 20 53 56 47 41 0a 20 20 00 c2 ---------------- Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 27 cm x 20 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Standard Timings: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Detailed Timing Descriptors: DTD 1: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz (277 mm x 208 mm) Hfront 40 Hsync 128 Hback 88 Hpol P Vfront 1 Vsync 4 Vback 23 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 59-61 Hz V, 36-38 kHz H, max dotclock 50 MHz Display Product Name: 'Linux SVGA' Checksum: 0xc2 So, an analog monitor EDID. However, if the connector was an HDMI monitor for example, it breaks the HDMI specification that requires, among other things, a digital display, the VIC 1 mode and an HDMI Forum Vendor Specific Data Block in an CTA-861 extension. We thus end up with a completely invalid EDID, which thus might confuse HDMI-related code that could parse it. After some discussions on IRC, we identified mainly two ways to fix this: - We can either create more EDIDs for each connector type to provide a built-in EDID that matches the resolution passed in the name, and still be a sensible EDID for that connector type; - Or we can just prevent the EDID to be exposed to userspace if it's built-in. Or possibly both. However, the conclusion was that maybe we just don't need the built-in EDIDs at all and we should just get rid of them. So here we are. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Maxime Ripard <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240221092636.691701-1-mripard@kernel.org diff 89ac522d Wed Feb 21 02:26:36 MST 2024 Maxime Ripard <mripard@kernel.org> drm/edid/firmware: Remove built-in EDIDs The EDID firmware loading mechanism introduced a few built-in EDIDs that could be forced on any connector, bypassing the EDIDs it exposes. While convenient, this limited set of EDIDs doesn't take into account the connector type, and we can end up with an EDID that is completely invalid for a given connector. For example, the edid/800x600.bin file matches the following EDID: edid-decode (hex): 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 05 16 01 03 6d 1b 14 78 ea 5e c0 a4 59 4a 98 25 20 50 54 01 00 00 45 40 01 01 01 01 01 01 01 01 01 01 01 01 01 01 a0 0f 20 00 31 58 1c 20 28 80 14 00 15 d0 10 00 00 1e 00 00 00 ff 00 4c 69 6e 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 3b 3d 24 26 05 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c 69 6e 75 78 20 53 56 47 41 0a 20 20 00 c2 ---------------- Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 27 cm x 20 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Standard Timings: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Detailed Timing Descriptors: DTD 1: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz (277 mm x 208 mm) Hfront 40 Hsync 128 Hback 88 Hpol P Vfront 1 Vsync 4 Vback 23 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 59-61 Hz V, 36-38 kHz H, max dotclock 50 MHz Display Product Name: 'Linux SVGA' Checksum: 0xc2 So, an analog monitor EDID. However, if the connector was an HDMI monitor for example, it breaks the HDMI specification that requires, among other things, a digital display, the VIC 1 mode and an HDMI Forum Vendor Specific Data Block in an CTA-861 extension. We thus end up with a completely invalid EDID, which thus might confuse HDMI-related code that could parse it. After some discussions on IRC, we identified mainly two ways to fix this: - We can either create more EDIDs for each connector type to provide a built-in EDID that matches the resolution passed in the name, and still be a sensible EDID for that connector type; - Or we can just prevent the EDID to be exposed to userspace if it's built-in. Or possibly both. However, the conclusion was that maybe we just don't need the built-in EDIDs at all and we should just get rid of them. So here we are. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Maxime Ripard <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240221092636.691701-1-mripard@kernel.org diff 89ac522d Wed Feb 21 02:26:36 MST 2024 Maxime Ripard <mripard@kernel.org> drm/edid/firmware: Remove built-in EDIDs The EDID firmware loading mechanism introduced a few built-in EDIDs that could be forced on any connector, bypassing the EDIDs it exposes. While convenient, this limited set of EDIDs doesn't take into account the connector type, and we can end up with an EDID that is completely invalid for a given connector. For example, the edid/800x600.bin file matches the following EDID: edid-decode (hex): 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 05 16 01 03 6d 1b 14 78 ea 5e c0 a4 59 4a 98 25 20 50 54 01 00 00 45 40 01 01 01 01 01 01 01 01 01 01 01 01 01 01 a0 0f 20 00 31 58 1c 20 28 80 14 00 15 d0 10 00 00 1e 00 00 00 ff 00 4c 69 6e 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 3b 3d 24 26 05 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c 69 6e 75 78 20 53 56 47 41 0a 20 20 00 c2 ---------------- Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 27 cm x 20 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Standard Timings: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Detailed Timing Descriptors: DTD 1: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz (277 mm x 208 mm) Hfront 40 Hsync 128 Hback 88 Hpol P Vfront 1 Vsync 4 Vback 23 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 59-61 Hz V, 36-38 kHz H, max dotclock 50 MHz Display Product Name: 'Linux SVGA' Checksum: 0xc2 So, an analog monitor EDID. However, if the connector was an HDMI monitor for example, it breaks the HDMI specification that requires, among other things, a digital display, the VIC 1 mode and an HDMI Forum Vendor Specific Data Block in an CTA-861 extension. We thus end up with a completely invalid EDID, which thus might confuse HDMI-related code that could parse it. After some discussions on IRC, we identified mainly two ways to fix this: - We can either create more EDIDs for each connector type to provide a built-in EDID that matches the resolution passed in the name, and still be a sensible EDID for that connector type; - Or we can just prevent the EDID to be exposed to userspace if it's built-in. Or possibly both. However, the conclusion was that maybe we just don't need the built-in EDIDs at all and we should just get rid of them. So here we are. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Maxime Ripard <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240221092636.691701-1-mripard@kernel.org diff 89ac522d Wed Feb 21 02:26:36 MST 2024 Maxime Ripard <mripard@kernel.org> drm/edid/firmware: Remove built-in EDIDs The EDID firmware loading mechanism introduced a few built-in EDIDs that could be forced on any connector, bypassing the EDIDs it exposes. While convenient, this limited set of EDIDs doesn't take into account the connector type, and we can end up with an EDID that is completely invalid for a given connector. For example, the edid/800x600.bin file matches the following EDID: edid-decode (hex): 00 ff ff ff ff ff ff 00 31 d8 00 00 00 00 00 00 05 16 01 03 6d 1b 14 78 ea 5e c0 a4 59 4a 98 25 20 50 54 01 00 00 45 40 01 01 01 01 01 01 01 01 01 01 01 01 01 01 a0 0f 20 00 31 58 1c 20 28 80 14 00 15 d0 10 00 00 1e 00 00 00 ff 00 4c 69 6e 75 78 20 23 30 0a 20 20 20 20 00 00 00 fd 00 3b 3d 24 26 05 00 0a 20 20 20 20 20 20 00 00 00 fc 00 4c 69 6e 75 78 20 53 56 47 41 0a 20 20 00 c2 ---------------- Block 0, Base EDID: EDID Structure Version & Revision: 1.3 Vendor & Product Identification: Manufacturer: LNX Model: 0 Made in: week 5 of 2012 Basic Display Parameters & Features: Analog display Signal Level Standard: 0.700 : 0.000 : 0.700 V p-p Blank level equals black level Sync: Separate Composite Serration Maximum image size: 27 cm x 20 cm Gamma: 2.20 DPMS levels: Standby Suspend Off RGB color display First detailed timing is the preferred timing Color Characteristics: Red : 0.6416, 0.3486 Green: 0.2919, 0.5957 Blue : 0.1474, 0.1250 White: 0.3125, 0.3281 Established Timings I & II: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Standard Timings: DMT 0x09: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz Detailed Timing Descriptors: DTD 1: 800x600 60.316541 Hz 4:3 37.879 kHz 40.000000 MHz (277 mm x 208 mm) Hfront 40 Hsync 128 Hback 88 Hpol P Vfront 1 Vsync 4 Vback 23 Vpol P Display Product Serial Number: 'Linux #0' Display Range Limits: Monitor ranges (GTF): 59-61 Hz V, 36-38 kHz H, max dotclock 50 MHz Display Product Name: 'Linux SVGA' Checksum: 0xc2 So, an analog monitor EDID. However, if the connector was an HDMI monitor for example, it breaks the HDMI specification that requires, among other things, a digital display, the VIC 1 mode and an HDMI Forum Vendor Specific Data Block in an CTA-861 extension. We thus end up with a completely invalid EDID, which thus might confuse HDMI-related code that could parse it. After some discussions on IRC, we identified mainly two ways to fix this: - We can either create more EDIDs for each connector type to provide a built-in EDID that matches the resolution passed in the name, and still be a sensible EDID for that connector type; - Or we can just prevent the EDID to be exposed to userspace if it's built-in. Or possibly both. However, the conclusion was that maybe we just don't need the built-in EDIDs at all and we should just get rid of them. So here we are. Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Jani Nikula <jani.nikula@intel.com> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Maxime Ripard <mripard@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20240221092636.691701-1-mripard@kernel.org diff 3fec6e59 Wed Feb 14 00:39:32 MST 2024 Nikhil V <quic_nprakash@quicinc.com> PM: hibernate: Support to select compression algorithm Currently the default compression algorithm is selected based on compile time options. Introduce a module parameter "hibernate.compressor" to override this behaviour. Different compression algorithms have different characteristics and hibernation may benefit when it uses any of these algorithms, especially when a secondary algorithm(LZ4) offers better decompression speeds over a default algorithm(LZO), which in turn reduces hibernation image restore time. Users can override the default algorithm in two ways: 1) Passing "hibernate.compressor" as kernel command line parameter. Usage: LZO: hibernate.compressor=lzo LZ4: hibernate.compressor=lz4 2) Specifying the algorithm at runtime. Usage: LZO: echo lzo > /sys/module/hibernate/parameters/compressor LZ4: echo lz4 > /sys/module/hibernate/parameters/compressor Currently LZO and LZ4 are the supported algorithms. LZO is the default compression algorithm used with hibernation. Signed-off-by: Nikhil V <quic_nprakash@quicinc.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> diff 2ed08e4b Tue Feb 20 23:08:59 MST 2024 Feng Tang <feng.tang@intel.com> clocksource: Scale the watchdog read retries automatically On a 8-socket server the TSC is wrongly marked as 'unstable' and disabled during boot time on about one out of 120 boot attempts: clocksource: timekeeping watchdog on CPU227: wd-tsc-wd excessive read-back delay of 153560ns vs. limit of 125000ns, wd-wd read-back delay only 11440ns, attempt 3, marking tsc unstable tsc: Marking TSC unstable due to clocksource watchdog TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'. sched_clock: Marking unstable (119294969739, 159204297)<-(125446229205, -5992055152) clocksource: Checking clocksource tsc synchronization from CPU 319 to CPUs 0,99,136,180,210,542,601,896. clocksource: Switched to clocksource hpet The reason is that for platform with a large number of CPUs, there are sporadic big or huge read latencies while reading the watchog/clocksource during boot or when system is under stress work load, and the frequency and maximum value of the latency goes up with the number of online CPUs. The cCurrent code already has logic to detect and filter such high latency case by reading the watchdog twice and checking the two deltas. Due to the randomness of the latency, there is a low probabilty that the first delta (latency) is big, but the second delta is small and looks valid. The watchdog code retries the readouts by default twice, which is not necessarily sufficient for systems with a large number of CPUs. There is a command line parameter 'max_cswd_read_retries' which allows to increase the number of retries, but that's not user friendly as it needs to be tweaked per system. As the number of required retries is proportional to the number of online CPUs, this parameter can be calculated at runtime. Scale and enlarge the number of retries according to the number of online CPUs and remove the command line parameter completely. [ tglx: Massaged change log and comments ] Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Jin Wang <jin1.wang@intel.com> Tested-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Waiman Long <longman@redhat.com> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/r/20240221060859.1027450-1-feng.tang@intel.com diff 3e3ede49 Fri Feb 02 20:21:13 MST 2024 Guilherme G. Piccoli <gpiccoli@igalia.com> docs: Document possible_cpus parameter The number of possible CPUs is set be kernel in early boot time through some discovery mechanisms, like ACPI in x86. We have a parameter both in x86 and S390 to override that - there are some cases of BIOSes exposing more possible CPUs than the available ones, so this parameter is a good testing mechanism, but for some reason wasn't mentioned so far in the kernel parameters guide - let's fix that. Cc: Changwoo Min <changwoo@igalia.com> Signed-off-by: "Guilherme G. Piccoli" <gpiccoli@igalia.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20240203152208.1461293-1-gpiccoli@igalia.com diff 78de91b4 Tue Jan 16 09:43:08 MST 2024 Youling Tang <tangyouling@kylinos.cn> LoongArch: Use generic interface to support crashkernel=X,[high,low] LoongArch already supports two crashkernel regions in kexec-tools, so we can directly use the common interface to support crashkernel=X,[high,low] after commit 0ab97169aa0517079b ("crash_core: add generic function to do reservation"). With the help of newly changed function parse_crashkernel() and generic reserve_crashkernel_generic(), crashkernel reservation can be simplified by steps: 1) Add a new header file <asm/crash_core.h>, then define CRASH_ALIGN, CRASH_ADDR_LOW_MAX and CRASH_ADDR_HIGH_MAX and in <asm/crash_core.h>; 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and reserve_crashkernel_generic(); 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in arch/loongarch/Kconfig. One can reserve the crash kernel from high memory above DMA zone range by explicitly passing "crashkernel=X,high"; or reserve a memory range below 4G with "crashkernel=X,low". Besides, there are few rules need to take notice: 1) "crashkernel=X,[high,low]" will be ignored if "crashkernel=size" is specified. 2) "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed and there is enough memory to be allocated under 4G. 3) When allocating crashkernel above 4G and no "crashkernel=X,low" is specified, a 128M low memory will be allocated automatically for swiotlb bounce buffer. See Documentation/admin-guide/kernel-parameters.txt for more information. Following test cases have been performed as expected: 1) crashkernel=256M //low=256M 2) crashkernel=1G //low=1G 3) crashkernel=4G //high=4G, low=128M(default) 4) crashkernel=4G crashkernel=256M,high //high=4G, low=128M(default), high is ignored 5) crashkernel=4G crashkernel=256M,low //high=4G, low=128M(default), low is ignored 6) crashkernel=4G,high //high=4G, low=128M(default) 7) crashkernel=256M,low //low=0M, invalid 8) crashkernel=4G,high crashkernel=256M,low //high=4G, low=256M 9) crashkernel=4G,high crashkernel=4G,low //high=0M, low=0M, invalid 10) crashkernel=512M@2560M //low=512M 11) crashkernel=1G,high crashkernel=0M,low //high=1G, low=0M Recommended usage in general: 1) In the case of small memory: crashkernel=512M 2) In the case of large memory: crashkernel=1024M,high crashkernel=128M,low Signed-off-by: Youling Tang <tangyouling@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> diff 78de91b4 Tue Jan 16 09:43:08 MST 2024 Youling Tang <tangyouling@kylinos.cn> LoongArch: Use generic interface to support crashkernel=X,[high,low] LoongArch already supports two crashkernel regions in kexec-tools, so we can directly use the common interface to support crashkernel=X,[high,low] after commit 0ab97169aa0517079b ("crash_core: add generic function to do reservation"). With the help of newly changed function parse_crashkernel() and generic reserve_crashkernel_generic(), crashkernel reservation can be simplified by steps: 1) Add a new header file <asm/crash_core.h>, then define CRASH_ALIGN, CRASH_ADDR_LOW_MAX and CRASH_ADDR_HIGH_MAX and in <asm/crash_core.h>; 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and reserve_crashkernel_generic(); 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in arch/loongarch/Kconfig. One can reserve the crash kernel from high memory above DMA zone range by explicitly passing "crashkernel=X,high"; or reserve a memory range below 4G with "crashkernel=X,low". Besides, there are few rules need to take notice: 1) "crashkernel=X,[high,low]" will be ignored if "crashkernel=size" is specified. 2) "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed and there is enough memory to be allocated under 4G. 3) When allocating crashkernel above 4G and no "crashkernel=X,low" is specified, a 128M low memory will be allocated automatically for swiotlb bounce buffer. See Documentation/admin-guide/kernel-parameters.txt for more information. Following test cases have been performed as expected: 1) crashkernel=256M //low=256M 2) crashkernel=1G //low=1G 3) crashkernel=4G //high=4G, low=128M(default) 4) crashkernel=4G crashkernel=256M,high //high=4G, low=128M(default), high is ignored 5) crashkernel=4G crashkernel=256M,low //high=4G, low=128M(default), low is ignored 6) crashkernel=4G,high //high=4G, low=128M(default) 7) crashkernel=256M,low //low=0M, invalid 8) crashkernel=4G,high crashkernel=256M,low //high=4G, low=256M 9) crashkernel=4G,high crashkernel=4G,low //high=0M, low=0M, invalid 10) crashkernel=512M@2560M //low=512M 11) crashkernel=1G,high crashkernel=0M,low //high=1G, low=0M Recommended usage in general: 1) In the case of small memory: crashkernel=512M 2) In the case of large memory: crashkernel=1024M,high crashkernel=128M,low Signed-off-by: Youling Tang <tangyouling@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> diff 78de91b4 Tue Jan 16 09:43:08 MST 2024 Youling Tang <tangyouling@kylinos.cn> LoongArch: Use generic interface to support crashkernel=X,[high,low] LoongArch already supports two crashkernel regions in kexec-tools, so we can directly use the common interface to support crashkernel=X,[high,low] after commit 0ab97169aa0517079b ("crash_core: add generic function to do reservation"). With the help of newly changed function parse_crashkernel() and generic reserve_crashkernel_generic(), crashkernel reservation can be simplified by steps: 1) Add a new header file <asm/crash_core.h>, then define CRASH_ALIGN, CRASH_ADDR_LOW_MAX and CRASH_ADDR_HIGH_MAX and in <asm/crash_core.h>; 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and reserve_crashkernel_generic(); 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in arch/loongarch/Kconfig. One can reserve the crash kernel from high memory above DMA zone range by explicitly passing "crashkernel=X,high"; or reserve a memory range below 4G with "crashkernel=X,low". Besides, there are few rules need to take notice: 1) "crashkernel=X,[high,low]" will be ignored if "crashkernel=size" is specified. 2) "crashkernel=X,low" is valid only when "crashkernel=X,high" is passed and there is enough memory to be allocated under 4G. 3) When allocating crashkernel above 4G and no "crashkernel=X,low" is specified, a 128M low memory will be allocated automatically for swiotlb bounce buffer. See Documentation/admin-guide/kernel-parameters.txt for more information. Following test cases have been performed as expected: 1) crashkernel=256M //low=256M 2) crashkernel=1G //low=1G 3) crashkernel=4G //high=4G, low=128M(default) 4) crashkernel=4G crashkernel=256M,high //high=4G, low=128M(default), high is ignored 5) crashkernel=4G crashkernel=256M,low //high=4G, low=128M(default), low is ignored 6) crashkernel=4G,high //high=4G, low=128M(default) 7) crashkernel=256M,low //low=0M, invalid 8) crashkernel=4G,high crashkernel=256M,low //high=4G, low=256M 9) crashkernel=4G,high crashkernel=4G,low //high=0M, low=0M, invalid 10) crashkernel=512M@2560M //low=512M 11) crashkernel=1G,high crashkernel=0M,low //high=1G, low=0M Recommended usage in general: 1) In the case of small memory: crashkernel=512M 2) In the case of large memory: crashkernel=1024M,high crashkernel=128M,low Signed-off-by: Youling Tang <tangyouling@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> |
/linux-master/init/ | ||
H A D | main.c | diff 3c2f8859 Sun Feb 25 16:07:31 MST 2024 Ingo Molnar <mingo@kernel.org> smp: Provide 'setup_max_cpus' definition on UP too This was already defined locally by init/main.c, but let's make it generic, as arch/x86/kernel/cpu/topology.c is going to make use of it to have more uniform code. Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> diff 941baf6f Thu Sep 08 12:21:54 MDT 2022 Alexey Dobriyan <adobriyan@gmail.com> proc: give /proc/cmdline size Most /proc files don't have length (in fstat sense). This leads to inefficiencies when reading such files with APIs commonly found in modern programming languages. They open file, then fstat descriptor, get st_size == 0 and either assume file is empty or start reading without knowing target size. cat(1) does OK because it uses large enough buffer by default. But naive programs copy-pasted from SO aren't: let mut f = std::fs::File::open("/proc/cmdline").unwrap(); let mut buf: Vec<u8> = Vec::new(); f.read_to_end(&mut buf).unwrap(); will result in openat(AT_FDCWD, "/proc/cmdline", O_RDONLY|O_CLOEXEC) = 3 statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address) statx(3, "", AT_STATX_SYNC_AS_STAT|AT_EMPTY_PATH, STATX_ALL, {stx_mask=STATX_BASIC_STATS|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFREG|0444, stx_size=0, ...}) = 0 lseek(3, 0, SEEK_CUR) = 0 read(3, "BOOT_IMAGE=(hd3,gpt2)/vmlinuz-5.", 32) = 32 read(3, "19.6-100.fc35.x86_64 root=/dev/m", 32) = 32 read(3, "apper/fedora_localhost--live-roo"..., 64) = 64 read(3, "ocalhost--live-swap rd.lvm.lv=fe"..., 128) = 116 read(3, "", 12) open/stat is OK, lseek looks silly but there are 3 unnecessary reads because Rust starts with 32 bytes per Vec<u8> and grows from there. In case of /proc/cmdline, the length is known precisely. Make variables readonly while I'm at it. P.S.: I tried to scp /proc/cpuinfo today and got empty file but this is separate story. Link: https://lkml.kernel.org/r/YxoywlbM73JJN3r+@localhost.localdomain Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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