Commit Graph

32 Commits

Author SHA1 Message Date
David Rientjes
071a4befeb mm, oom: do not panic for oom kills triggered from sysrq
Sysrq+f is used to kill a process either for debug or when the VM is
otherwise unresponsive.

It is not intended to trigger a panic when no process may be killed.

Avoid panicking the system for sysrq+f when no processes are killed.

Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Michal Hocko <mhocko@suse.cz>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-08 15:35:28 -07:00
James Hogan
0f6ce77538 Documentation/sysrq.txt: Mention MIPS TLB dump (x)
Commit d1e9a4f547 ("MIPS: Add SysRq operation to dump TLBs on all
CPUs") added the 'x' sysrq key for dumping MIPS TLB entries, but didn't
document it in Documentation/sysrq.txt.

Add mention of the MIPS use of the 'x' SysRq key.

Reported-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: linux-doc@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10720/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-09-03 12:07:43 +02:00
Ben Hutchings
8eaede49df sysrq: Allow magic SysRq key functions to be disabled through Kconfig
Turn the initial value of sysctl kernel.sysrq (SYSRQ_DEFAULT_ENABLE)
into a Kconfig variable.

Original version by Bastian Blank <waldi@debian.org>.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-16 13:01:44 -07:00
Ben Hutchings
e8b5cbb041 sysrq: Document hexadecimal values for kernel.sysrq bitmask
It makes more sense to enter a bitmask in hexadecimal rather than
decimal.  Sadly we can't make it read back as hexadecimal.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-10-16 13:01:44 -07:00
zhangwei(Jovi)
e2a8b0a779 Documentation/sysrq: fix inconstistent help message of sysrq key
Currently help message of /proc/sysrq-trigger highlight its
upper-case characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch fix sysrq documentation.

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-30 17:04:10 -07:00
David S. Miller
916ca14aaf sparc64: Add global PMU register dumping via sysrq.
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-10-16 09:34:01 -07:00
Randy Dunlap
21106b0114 Documentation: sysrq: Crutcher Dunnavant is unavailable
Reported-by: Křištof Želechovski <giecrilj@stegny.2a.pl>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-30 16:03:15 -07:00
Randy Dunlap
003bb8ab7c documentation: update sysrq.txt magic sysrq keys
Update Documentation/sysrq.txt magic sysrq keys:

 - 'g' is for kgdb (not arch-specific);
 - add 2 new uses for 'v', remove the Voyager info;
 - add 'y' info (SPARC-64 specific);

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "James E.J. Bottomley" <James.Bottomley@suse.de>
Cc: David Airlie <airlied@linux.ie>
Acked-by: Alexander Shishkin <virtuoso@slind.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-26 17:32:41 -07:00
Paul Fox
a2056ffd4a Input: Documentation/sysrq.txt - update KEY_SYSRQ info
While setting up sysrq operation on the XO laptop (which lacks a SysRq
key), i realized that the documentation was quite out of date.

Change documentation of SysRq to reflect current KEY_SYSRQ value.

Signed-off-by: Paul Fox <pgf@laptop.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-05-19 10:14:15 -07:00
Hidetoshi Seto
cab8bd3410 sysrq, kdump: make sysrq-c consistent
commit d6580a9f15 ("kexec: sysrq: simplify
sysrq-c handler") changed the behavior of sysrq-c to unconditional
dereference of NULL pointer.  So in cases with CONFIG_KEXEC, where
crash_kexec() was directly called from sysrq-c before, now it can be said
that a step of "real oops" was inserted before starting kdump.

However, in contrast to oops via SysRq-c from keyboard which results in
panic due to in_interrupt(), oops via "echo c > /proc/sysrq-trigger" will
not become panic unless panic_on_oops=1.  It means that even if dump is
properly configured to be taken on panic, the sysrq-c from proc interface
might not start crashdump while the sysrq-c from keyboard can start
crashdump.  This confuses traditional users of kdump, i.e.  people who
expect sysrq-c to do common behavior in both of the keyboard and proc
interface.

This patch brings the keyboard and proc interface behavior of sysrq-c in
line, by forcing panic_on_oops=1 before oops in sysrq-c handler.

And some updates in documentation are included, to clarify that there is
no longer dependency with CONFIG_KEXEC, and that now the system can just
crash by sysrq-c if no dump mechanism is configured.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Brayan Arraes <brayan@yack.com.br>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-29 19:10:36 -07:00
Ingo Molnar
8302294f43 Merge branch 'tracing/core-v2' into tracing-for-linus
Conflicts:
	include/linux/slub_def.h
	lib/Kconfig.debug
	mm/slob.c
	mm/slub.c
2009-04-02 00:49:02 +02:00
Eric Sandeen
c2d7543851 filesystem freeze: allow SysRq emergency thaw to thaw frozen filesystems
Now that the filesystem freeze operation has been elevated to the VFS, and
is just an ioctl away, some sort of safety net for unintentionally frozen
root filesystems may be in order.

The timeout thaw originally proposed did not get merged, but perhaps
something like this would be useful in emergencies.

For example, freeze /path/to/mountpoint may freeze your root filesystem if
you forgot that you had that unmounted.

I chose 'j' as the last remaining character other than 'h' which is sort
of reserved for help (because help is generated on any unknown character).

I've tested this on a non-root fs with multiple (nested) freezers, as well
as on a system rendered unresponsive due to a frozen root fs.

[randy.dunlap@oracle.com: emergency thaw only if CONFIG_BLOCK enabled]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Takashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-01 08:59:17 -07:00
Ingo Molnar
4092762aeb Merge branch 'tracing/ftrace'; commit 'v2.6.29-rc2' into tracing/core 2009-01-18 20:15:05 +01:00
Andy Whitcroft
47c33d9c19 sysrq documentation: document why the command header only is shown
Document the interactions between loglevel and the sysrq output.  Also
document how to work round it should output be required on the console.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Martin Mares <mj@ucw.cz>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-15 16:39:36 -08:00
Andy Whitcroft
89365e2641 sysrq documentation: remove the redundant updated date
git is maintaining the last update time much more accuratly than the
internal update time.  Remove it.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-15 16:39:36 -08:00
Randy Dunlap
3871f2ffe5 sysrq: fix ftrace help msg & doc.
Impact: update documentation and help messages

We have a conventional method of explicitly stating the
sysrq action key in a sysrq help message, so change
dump-ftrace-buffer to use that method and add it to
Documentation/sysrq.txt.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-26 10:27:22 +01:00
Linus Torvalds
99ebcf8285 Merge branch 'v28-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'v28-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (36 commits)
  fix documentation of sysrq-q really
  Fix documentation of sysrq-q
  timer_list: add base address to clock base
  timer_list: print cpu number of clockevents device
  timer_list: print real timer address
  NOHZ: restart tick device from irq_enter()
  NOHZ: split tick_nohz_restart_sched_tick()
  NOHZ: unify the nohz function calls in irq_enter()
  timers: fix itimer/many thread hang, fix
  timers: fix itimer/many thread hang, v3
  ntp: improve adjtimex frequency rounding
  timekeeping: fix rounding problem during clock update
  ntp: let update_persistent_clock() sleep
  hrtimer: reorder struct hrtimer to save 8 bytes on 64bit builds
  posix-timers: lock_timer: make it readable
  posix-timers: lock_timer: kill the bogus ->it_id check
  posix-timers: kill ->it_sigev_signo and ->it_sigev_value
  posix-timers: sys_timer_create: cleanup the error handling
  posix-timers: move the initialization of timer->sigq from send to create path
  posix-timers: sys_timer_create: simplify and s/tasklist/rcu/
  ...

Fix trivial conflicts due to sysrq-q description clahes in
Documentation/sysrq.txt and drivers/char/sysrq.c
2008-10-20 13:19:56 -07:00
Andi Kleen
2a80a3783d Fix documentation of sysrq-q
I fell into the trap recently that it only dumps hrtimers instead of
all timers. Fix the documentation.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-20 08:52:34 -07:00
Thomas Gleixner
322acf6585 fix documentation of sysrq-q really
SysRq-Q also dumps information about the clockevent devices.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-20 12:44:32 +02:00
Andi Kleen
24bdeb4598 Fix documentation of sysrq-q
I fell into the trap recently that it only dumps hrtimers instead of
all timers. Fix the documentation.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: torvalds@linux-foundation.org
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-10-20 12:44:32 +02:00
Rik van Riel
5045bcae0f sysrq: add show-backtrace-on-all-cpus function
SysRQ-P is not always useful on SMP systems, since it usually ends up showing
the backtrace of a CPU that is doing just fine, instead of the backtrace of
the CPU that is having problems.

This patch adds SysRQ show-all-cpus(L), which shows the backtrace of every
active CPU in the system.  It skips idle CPUs because some SMP systems are
just too large and we already know what the backtrace of the idle task looks
like.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Rik van Riel <riel@redhat.com>
Randy Dunlap <randy.dunlap@oracle.com>
Cc: <lwoodman@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-29 08:06:03 -07:00
Pavel Machek
dfb0042d43 sysrq docs: document sequence that actually works
Document sequence of keypresses that actually works. Yes, this changed
year-or-so ago.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-07 16:28:43 -07:00
Jesper Juhl
09736bd36a Documentation: sysrq, description of 'h' slightly inaccurate
In Documentation/sysrq.txt, the description of 'h' says that any key not
listed *above* will generate help.  That's obviously not true since all the
keys listed below 'h' will do what they are described to do, not display help.
 So change the text so that it says that any key not listed in the table will
generate help, which is what really happens.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-08-11 15:47:41 -07:00
Paul Mundt
d29c91c70b doc: Update sysrq doc for sh kgdb trigger.
sh uses the same sysrq trigger as ppc, update the documentation to
reflect that.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
2007-05-07 02:10:53 +00:00
Johannes Weiner
acf11faeb1 [PATCH] Documentation/sysrq.txt: added short description for 'Q' (timerlist)
I added the 'Q' to list. A short description in the `Ok, so what can I
use them for'-section, on when or why to use it would be nice!

Signed-off-by: Johannes Weiner <hannes-kernel@saeurebad.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-22 19:39:05 -07:00
Randy Dunlap
78831ba682 [PATCH] sysrq: alphabetize command keys doc
Alphabetize the sysrq command keys list.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:32 -08:00
Randy Dunlap
d346cce308 [PATCH] sysrq: showBlockedTasks is sysrq-W
Change SysRq showBlockedTasks from sysrq-X to sysrq-W and show that in the
Help message.

It was previously done via X, but X is already used for Xmon on ppc & powerpc
platforms and this collision needs to be avoided.

All callers of register_sysrq_key() are now marked in the sysrq op/key table.
I didn't mark 'h' as Help because Help is just printed for any unknown key,
such as '?'.

Added some omitted sysrq key entries in the sysrq.txt file.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-01 16:22:42 -08:00
Jesper Juhl
3eecd1dc57 [PATCH] Correct sa'K' description in sysrq.txt
sysrq SAK is described as being something you should mistake for SAK from
c2 compliant systems - whoops.  What's meant is that it should *not* be
mistaken as such.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25 10:01:13 -07:00
Adam D. Moss
5e03e2c48f update for Documentation/sysrq.txt
This patch for 2.4.x updates the dead email address for 'Mydraal'
and since he no longer wishes to field questions concerning
SysRq or this document removes the statement stating otherwise.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-01-03 13:31:01 +01:00
Adrian Bunk
338cec3253 [PATCH] merge some from Rusty's trivial patches
This patch contains the most trivial from Rusty's trivial patches:
- spelling fixes
- remove duplicate includes

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:30 -07:00
Hariprasad Nellitheertha
86b1ae38c0 [PATCH] kdump: sysrq trigger mechanism for kexec based crashdumps
Add a sysrq-trigger mechanism for kexec based crashdumps.  Alt-Sysrq-c
triggers a kexec based crashdump.

Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:54 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00