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2020-04-16doc/admin-guide: update kernel.rst with CAP_PERFMON informationAlexey Budankov
Update the kernel.rst documentation file with the information related to usage of CAP_PERFMON capability to secure performance monitoring and observability operations in system. Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Igor Lubashev <ilubashe@akamai.com> Cc: James Morris <jmorris@namei.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Serge Hallyn <serge@hallyn.com> Cc: Song Liu <songliubraving@fb.com> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: intel-gfx@lists.freedesktop.org Cc: linux-doc@vger.kernel.org Cc: linux-man@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: selinux@vger.kernel.org Link: http://lore.kernel.org/lkml/84c32383-14a2-fa35-16b6-f9e59bd37240@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-04-15docs: admin-guide: merge sections for the kernel.modprobe sysctlEric Biggers
Documentation for the kernel.modprobe sysctl was added both by commit 0317c5371e6a ("docs: merge debugging-modules.txt into sysctl/kernel.rst") and by commit 6e7158250625 ("docs: admin-guide: document the kernel.modprobe sysctl"), resulting in the same sysctl being documented in two places. Merge these into one place. Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Stephen Kitt <steve@sk2.org> Link: https://lore.kernel.org/r/20200414172430.230293-1-ebiggers@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-04-10docs: admin-guide: document the kernel.modprobe sysctlEric Biggers
Document the kernel.modprobe sysctl in the same place that all the other kernel.* sysctls are documented. Make sure to mention how to use this sysctl to completely disable module autoloading, and how this sysctl relates to CONFIG_STATIC_USERMODEHELPER. [ebiggers@google.com: v5] Link: http://lkml.kernel.org/r/20200318230515.171692-4-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jeff Vander Stoep <jeffv@google.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: NeilBrown <neilb@suse.com> Link: http://lkml.kernel.org/r/20200312202552.241885-4-ebiggers@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-03-10Documentation: Better document the softlockup_panic sysctlGuilherme G. Piccoli
Commit 9c44bc03fff4 ("softlockup: allow panic on lockup") added the softlockup_panic sysctl, but didn't add information about it to the file Documentation/admin-guide/sysctl/kernel.rst (which in that time certainly wasn't rst and had other name!). This patch just adds the respective documentation and references it from the corresponding entry in Documentation/admin-guide/kernel-parameters.txt. This patch was strongly based on Scott Wood's commit d22881dc13b6 ("Documentation: Better document the hardlockup_panic sysctl"). Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> Link: https://lore.kernel.org/r/20200310183649.23163-1-gpiccoli@canonical.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-25docs: add a script to check sysctl docsStephen Kitt
This script allows sysctl documentation to be checked against the kernel source code, to identify missing or obsolete entries. Running it against 5.5 shows for example that sysctl/kernel.rst has two obsolete entries and is missing 52 entries. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-25docs: sysctl/kernel: document acpi_video_flagsStephen Kitt
Based on the implementation in arch/x86/kernel/acpi/sleep.c, in particular the acpi_sleep_setup() function. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: sysctl/kernel: remove rtsig entriesStephen Kitt
These have no corresponding code in the kernel. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: document panic fully in sysctl/kernel.rstStephen Kitt
The description of panic doesn’t cover all the supported scenarios; this patch fixes that, describing the three possibilities (no reboot, immediate reboot, reboot after a delay). Based on the implementation in kernel/panic.c. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: document stop-a in sysctl/kernel.rstStephen Kitt
This describes the SPARC-specific stop-a sysctl entry, which was previously listed in kernel.rst but not documented. Base on the implementation in arch/sparc/kernel/setup_{32,64}.c and kernel/panic.c. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: add missing IPC documentation in sysctl/kernel.rstStephen Kitt
This adds short descriptions of msgmax, msgmnb, msgmni, and shmmni, which were previously listed in kernel.rst but not described. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: drop l2cr from sysctl/kernel.rstStephen Kitt
The l2cr sysctl entry was removed in commit c2f3dabefa73 ("sysctl: kill binary sysctl KERN_PPC_L2CR"), this removes the corresponding documentation. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: merge debugging-modules.txt into sysctl/kernel.rstStephen Kitt
This fits nicely in sysctl/kernel.rst, merge it (and rephrase it) instead of linking to it. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19docs: pretty up sysctl/kernel.rstStephen Kitt
This updates sysctl/kernel.rst to use ReStructured Text more fully: * the list of files is now the table of contents (old entries with no corresponding sections are added as empty sections for now); * code references and commands are formatted as code, except for function names which end up linked to the appropriate documentation; * links are used to point to other documentation and other sections; * tables are used to make lists of values more readable (as already done for some sections); * in heavily-reworked paragraphs, sentences are wrapped individually, to make future diffs easier to read. The first mention of the kernel version is dropped. The second mention, saying that the document is accurate for 2.2, is preserved for now; I will update that once the document really is accurate for a current kernel release. Signed-off-by: Stephen Kitt <steve@sk2.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-13docs: admin-guide: Add description of %c corename formatd.hatayama@fujitsu.com
There is somehow no description of %c corename format specifier for /proc/sys/kernel/core_pattern. The %c corename format specifier is used by user-space application such as systemd-coredump, so it should be documented. To find where %c is handled in the kernel source code, look at function format_corename() in fs/coredump.c. Signed-off-by: HATAYAMA Daisuke <d.hatayama@fujitsu.com> Link: https://lore.kernel.org/r/TYAPR01MB4014714BB2ACE425BB6EC6B7951A0@TYAPR01MB4014.jpnprd01.prod.outlook.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-11-07docs: admin-guide: Remove threads-max auto-tuningMasanari Iida
Since following path was merged in 5.4-rc3, auto-tuning feature in threads-max does not exist any more. Fix the admin-guide document as is. kernel/sysctl.c: do not override max_threads provided by userspace b0f53dbc4bc4c371f38b14c391095a3bb8a0bb40 Fixes: b0f53dbc4bc4 ("kernel/sysctl.c: do not override max_threads provided by userspace") Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-11-07docs: admin-guide: Fix min value of threads-max in kernel.rstMasanari Iida
Since following patch was merged 5.4-rc3, minimum value for threads-max changed to 1. kernel/sysctl.c: do not override max_threads provided by userspace b0f53dbc4bc4c371f38b14c391095a3bb8a0bb40 Fixes: b0f53dbc4bc4 ("kernel/sysctl.c: do not override max_threads provided by userspace") Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-10-10docs: admin-guide: fix printk_ratelimit explanationOleksandr Natalenko
The printk_ratelimit value accepts seconds, not jiffies (though it is converted into jiffies internally). Update documentation to reflect this. Also, remove the statement about allowing 1 message in 5 seconds since bursts up to 10 messages are allowed by default. Finally, while we are here, mention default value for printk_ratelimit_burst too. Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-07-15docs: admin-guide: add a series of orphaned documentsMauro Carvalho Chehab
There are lots of documents that belong to the admin-guide but are on random places (most under Documentation root dir). Move them to the admin guide. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
2019-07-15docs: admin-guide: move sysctl directory to itMauro Carvalho Chehab
The stuff under sysctl describes /sys interface from userspace point of view. So, add it to the admin-guide and remove the :orphan: from its index file. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>