Commit Graph

23 Commits

Author SHA1 Message Date
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