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9dcc38e2 |
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10-Dec-2021 |
Drew DeVault <sir@cmpwn.com> |
Increase default MLOCK_LIMIT to 8 MiB
This limit has not been updated since 2008, when it was increased to 64
KiB at the request of GnuPG. Until recently, the main use-cases for this
feature were (1) preventing sensitive memory from being swapped, as in
GnuPG's use-case; and (2) real-time use-cases. In the first case, little
memory is called for, and in the second case, the user is generally in a
position to increase it if they need more.
The introduction of IOURING_REGISTER_BUFFERS adds a third use-case:
preparing fixed buffers for high-performance I/O. This use-case will take
as much of this memory as it can get, but is still limited to 64 KiB by
default, which is very little. This increases the limit to 8 MB, which
was chosen fairly arbitrarily as a more generous, but still conservative,
default value.
It is also possible to raise this limit in userspace. This is easily
done, for example, in the use-case of a network daemon: systemd, for
instance, provides for this via LimitMEMLOCK in the service file; OpenRC
via the rc_ulimit variables. However, there is no established userspace
facility for configuring this outside of daemons: end-user applications do
not presently have access to a convenient means of raising their limits.
The buck, as it were, stops with the kernel. It's much easier to address
it here than it is to bring it to hundreds of distributions, and it can
only realistically be relied upon to be high-enough by end-user software
if it is more-or-less ubiquitous. Most distros don't change this
particular rlimit from the kernel-supplied default value, so a change here
will easily provide that ubiquity.
Link: https://lkml.kernel.org/r/20211028080813.15966-1-sir@cmpwn.com
Signed-off-by: Drew DeVault <sir@cmpwn.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Andrew Dona-Couch <andrew@donacou.ch>
Cc: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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| #
bdd565f8 |
|
25-Oct-2019 |
Arnd Bergmann <arnd@arndb.de> |
y2038: rusage: use __kernel_old_timeval
There are two 'struct timeval' fields in 'struct rusage'.
Unfortunately the definition of timeval is now ambiguous when used in
user space with a libc that has a 64-bit time_t, and this also changes
the 'rusage' definition in user space in a way that is incompatible with
the system call interface.
While there is no good solution to avoid all ambiguity here, change
the definition in the kernel headers to be compatible with the kernel
ABI, using __kernel_old_timeval as an unambiguous base type.
In previous discussions, there was also a plan to add a replacement
for rusage based on 64-bit timestamps and nanosecond resolution,
i.e. 'struct __kernel_timespec'. I have patches for that as well,
if anyone thinks we should do that.
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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| #
6f52b16c |
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01-Nov-2017 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
License cleanup: add SPDX license identifier to uapi header files with no license
Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.
By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:
NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".
otherwise syscall usage would not be possible.
Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne. See the previous patch in this series for the
methodology of how this patch was researched.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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