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  1. 07 Mar, 2012 3 commits
  3. 06 Mar, 2012 17 commits
  5. 05 Mar, 2012 20 commits
    • Linus Torvalds's avatar
      Merge branch 'akpm' (Andrew's patch bomb) · 3e85fb9c
      Linus Torvalds authored 
      Merge the emailed seties of 19 patches from Andrew Morton

* akpm:
  rapidio/tsi721: fix queue wrapping bug in inbound doorbell handler
  memcg: fix mapcount check in move charge code for anonymous page
  mm: thp: fix BUG on mm->nr_ptes
  alpha: fix 32/64-bit bug in futex support
  memcg: fix GPF when cgroup removal races with last exit
  debugobjects: Fix selftest for static warnings
  floppy/scsi: fix setting of BIO flags
  memcg: fix deadlock by inverting lrucare nesting
  drivers/rtc/rtc-r9701.c: fix crash in r9701_remove()
  c2port: class_create() returns an ERR_PTR
  pps: class_create() returns an ERR_PTR, not NULL
  hung_task: fix the broken rcu_lock_break() logic
  vfork: kill PF_STARTING
  coredump_wait: don't call complete_vfork_done()
  vfork: make it killable
  vfork: introduce complete_vfork_done()
  aio: wake up waiters when freeing unused kiocbs
  kprobes: return proper error code from register_kprobe()
  kmsg_dump: don't run on non-error paths by default
      3e85fb9c
    • Alexandre Bounine's avatar
      rapidio/tsi721: fix queue wrapping bug in inbound doorbell handler · b24823e6
      Alexandre Bounine authored 
      Fix a bug that causes a kernel panic when the number of received doorbells
is larger than number of entries in the inbound doorbell queue (current
default value = 512).

Another possible indication for this bug is large number of spurious
doorbells reported by tsi721 driver after reaching the queue size maximum.
Signed-off-by: default avatarAlexandre Bounine <alexandre.bounine@idt.com>
Cc: Chul Kim <chul.kim@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: <stable@vger.kernel.org>		[3.2.x+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b24823e6
    • Naoya Horiguchi's avatar
      memcg: fix mapcount check in move charge code for anonymous page · e6ca7b89
      Naoya Horiguchi authored 
      Currently the charge on shared anonyous pages is supposed not to moved in
task migration.  To implement this, we need to check that mapcount > 1,
instread of > 2.  So this patch fixes it.
Signed-off-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: default avatarDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e6ca7b89
    • Andrea Arcangeli's avatar
      mm: thp: fix BUG on mm->nr_ptes · 1c641e84
      Andrea Arcangeli authored 
      Dave Jones reports a few Fedora users hitting the BUG_ON(mm->nr_ptes...)
in exit_mmap() recently.

Quoting Hugh's discovery and explanation of the SMP race condition:

  "mm->nr_ptes had unusual locking: down_read mmap_sem plus
   page_table_lock when incrementing, down_write mmap_sem (or mm_users
   0) when decrementing; whereas THP is careful to increment and
   decrement it under page_table_lock.

   Now most of those paths in THP also hold mmap_sem for read or write
   (with appropriate checks on mm_users), but two do not: when
   split_huge_page() is called by hwpoison_user_mappings(), and when
   called by add_to_swap().

   It's conceivable that the latter case is responsible for the
   exit_mmap() BUG_ON mm->nr_ptes that has been reported on Fedora."

The simplest way to fix it without having to alter the locking is to make
split_huge_page() a noop in nr_ptes terms, so by counting the preallocated
pagetables that exists for every mapped hugepage.  It was an arbitrary
choice not to count them and either way is not wrong or right, because
they are not used but they're still allocated.
Reported-by: default avatarDave Jones <davej@redhat.com>
Reported-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: <stable@vger.kernel.org>	[3.0.x, 3.1.x, 3.2.x]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      1c641e84
    • Andrew Morton's avatar
      alpha: fix 32/64-bit bug in futex support · 62aca403
      Andrew Morton authored 
      Michael Cree said:

: : I have noticed some user space problems (pulseaudio crashes in pthread
: : code, glibc/nptl test suite failures, java compiler freezes on SMP alpha
: : systems) that arise when using a 2.6.39 or later kernel on Alpha.
: : Bisecting between 2.6.38 and 2.6.39 (using glibc/nptl test suite as
: : criterion for good/bad kernel) eventually leads to:
: :
: : 8d7718aa is the first bad commit
: : commit 8d7718aa
: : Author: Michel Lespinasse <walken@google.com>
: : Date:   Thu Mar 10 18:50:58 2011 -0800
: :
: :     futex: Sanitize futex ops argument types
: :
: :     Change futex_atomic_op_inuser and futex_atomic_cmpxchg_inatomic
: :     prototypes to use u32 types for the futex as this is the data type the
: :     futex core code uses all over the place.
: :
: : Looking at the commit I see there is a change of the uaddr argument in
: : the Alpha architecture specific code for futexes from int to u32, but I
: : don't see why this should cause a problem.

Richard Henderson said:

: futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
:                               u32 oldval, u32 newval)
: ...
:         :       "r"(uaddr), "r"((long)oldval), "r"(newval)
:
:
: There is no 32-bit compare instruction.  These are implemented by
: consistently extending the values to a 64-bit type.  Since the
: load instruction sign-extends, we want to sign-extend the other
: quantity as well (despite the fact it's logically unsigned).
:
: So:
:
: -        :       "r"(uaddr), "r"((long)oldval), "r"(newval)
: +        :       "r"(uaddr), "r"((long)(int)oldval), "r"(newval)
:
: should do the trick.

Michael said:

: This fixes the glibc test suite failures and the pulseaudio related
: crashes, but it does not fix the java compiiler lockups that I was (and
: are still) observing.  That is some other problem.
Reported-by: default avatarMichael Cree <mcree@orcon.net.nz>
Tested-by: default avatarMichael Cree <mcree@orcon.net.nz>
Acked-by: default avatarPhil Carmody <ext-phil.2.carmody@nokia.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Reviewed-by: default avatarMatt Turner <mattst88@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      62aca403
    • Hugh Dickins's avatar
      memcg: fix GPF when cgroup removal races with last exit · 7512102c
      Hugh Dickins authored 
      When moving tasks from old memcg (with move_charge_at_immigrate on new
memcg), followed by removal of old memcg, hit General Protection Fault in
mem_cgroup_lru_del_list() (called from release_pages called from
free_pages_and_swap_cache from tlb_flush_mmu from tlb_finish_mmu from
exit_mmap from mmput from exit_mm from do_exit).

Somewhat reproducible, takes a few hours: the old struct mem_cgroup has
been freed and poisoned by SLAB_DEBUG, but mem_cgroup_lru_del_list() is
still trying to update its stats, and take page off lru before freeing.

A task, or a charge, or a page on lru: each secures a memcg against
removal.  In this case, the last task has been moved out of the old memcg,
and it is exiting: anonymous pages are uncharged one by one from the
memcg, as they are zapped from its pagetables, so the charge gets down to
0; but the pages themselves are queued in an mmu_gather for freeing.

Most of those pages will be on lru (and force_empty is careful to
lru_add_drain_all, to add pages from pagevec to lru first), but not
necessarily all: perhaps some have been isolated for page reclaim, perhaps
some isolated for other reasons.  So, force_empty may find no task, no
charge and no page on lru, and let the removal proceed.

There would still be no problem if these pages were immediately freed; but
typically (and the put_page_testzero protocol demands it) they have to be
added back to lru before they are found freeable, then removed from lru
and freed.  We don't see the issue when adding, because the
mem_cgroup_iter() loops keep their own reference to the memcg being
scanned; but when it comes to mem_cgroup_lru_del_list().

I believe this was not an issue in v3.2: there, PageCgroupAcctLRU and
PageCgroupUsed flags were used (like a trick with mirrors) to deflect view
of pc->mem_cgroup to the stable root_mem_cgroup when neither set.
38c5d72f ("memcg: simplify LRU handling by new rule") mercifully
removed those convolutions, but left this General Protection Fault.

But it's surprisingly easy to restore the old behaviour: just check
PageCgroupUsed in mem_cgroup_lru_add_list() (which decides on which lruvec
to add), and reset pc to root_mem_cgroup if page is uncharged.  A risky
change?  just going back to how it worked before; testing, and an audit of
uses of pc->mem_cgroup, show no problem.

And there's a nice bonus: with mem_cgroup_lru_add_list() itself making
sure that an uncharged page goes to root lru, mem_cgroup_reset_owner() no
longer has any purpose, and we can safely revert 4e5f01c2 ("memcg:
clear pc->mem_cgroup if necessary").

Calling update_page_reclaim_stat() after add_page_to_lru_list() in swap.c
is not strictly necessary: the lru_lock there, with RCU before memcg
structures are freed, makes mem_cgroup_get_reclaim_stat_from_page safe
without that; but it seems cleaner to rely on one dependency less.
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7512102c
    • Stephen Boyd's avatar
      debugobjects: Fix selftest for static warnings · 9f78ff00
      Stephen Boyd authored 
      debugobjects is now printing a warning when a fixup for a NOTAVAILABLE
object is run.  This causes the selftest to fail like:

	ODEBUG: selftest warnings failed 4 != 5

We could just increase the number of warnings that the selftest is
expecting to see because that is actually what has changed.  But, it turns
out that fixup_activate() was written with inverted logic and thus a fixup
for a static object returned 1 indicating the object had been fixed, and 0
otherwise.  Fix the logic to be correct and update the counts to reflect
that nothing needed fixing for a static object.
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Reported-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9f78ff00
    • Muthu Kumar's avatar
      floppy/scsi: fix setting of BIO flags · 9354f1b8
      Muthu Kumar authored 
      Fix setting bio flags in drivers (sd_dif/floppy).
Signed-off-by: default avatarMuthukumar R <muthur@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9354f1b8
    • Hugh Dickins's avatar
      memcg: fix deadlock by inverting lrucare nesting · 9ce70c02
      Hugh Dickins authored 
      We have forgotten the rules of lock nesting: the irq-safe ones must be
taken inside the non-irq-safe ones, otherwise we are open to deadlock:

CPU0                          CPU1
----                          ----
lock(&(&pc->lock)->rlock);
                              local_irq_disable();
                              lock(&(&zone->lru_lock)->rlock);
                              lock(&(&pc->lock)->rlock);
<Interrupt>
lock(&(&zone->lru_lock)->rlock);

To check a different locking issue, I happened to add a spin_lock to
memcg's bit_spin_lock in lock_page_cgroup(), and lockdep very quickly
complained about __mem_cgroup_commit_charge_lrucare() (on CPU1 above).

So delete __mem_cgroup_commit_charge_lrucare(), passing a bool lrucare to
__mem_cgroup_commit_charge() instead, taking zone->lru_lock under
lock_page_cgroup() in the lrucare case.

The original was using spin_lock_irqsave, but we'd be in more trouble if
it were ever called at interrupt time: unconditional _irq is enough.  And
ClearPageLRU before del from lru, SetPageLRU before add to lru: no strong
reason, but that is the ordering used consistently elsewhere.

Fixes 36b62ad5 ("memcg: simplify corner case handling
of LRU").
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9ce70c02
    • Anatolij Gustschin's avatar
      drivers/rtc/rtc-r9701.c: fix crash in r9701_remove() · 73737b87
      Anatolij Gustschin authored 
      If probing the RTC didn't succeed due to failed RTC register access, the
RTC device will be unregistered.  Then, when removing the module
r9701_remove() causes a kernel crash while trying to unregister a not
registered RTC device.  Fix this by doing RTC register access test before
RTC device registration.
Signed-off-by: default avatarAnatolij Gustschin <agust@denx.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      73737b87
    • Dan Carpenter's avatar
      c2port: class_create() returns an ERR_PTR · 22ea71d7
      Dan Carpenter authored 
      class_create() doesn't return a NULL, it only returns ERR_PTRs.
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      22ea71d7
    • Dan Carpenter's avatar
      pps: class_create() returns an ERR_PTR, not NULL · 7ad12566
      Dan Carpenter authored 
      class_create() never returns NULLs only ERR_PTRs.
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7ad12566
    • Oleg Nesterov's avatar
      hung_task: fix the broken rcu_lock_break() logic · 6027ce49
      Oleg Nesterov authored 
      check_hung_uninterruptible_tasks()->rcu_lock_break() introduced by
"softlockup: check all tasks in hung_task" commit ce9dbe24 looks
absolutely wrong.

	- rcu_lock_break() does put_task_struct(). If the task has exited
	  it is not safe to even read its ->state, nothing protects this
	  task_struct.

	- The TASK_DEAD checks are wrong too. Contrary to the comment, we
	  can't use it to check if the task was unhashed. It can be unhashed
	  without TASK_DEAD, or it can be valid with TASK_DEAD.

	  For example, an autoreaping task can do release_task(current)
	  long before it sets TASK_DEAD in do_exit().

	  Or, a zombie task can have ->state == TASK_DEAD but release_task()
	  was not called, and in this case we must not break the loop.

Change this code to check pid_alive() instead, and do this before we drop
the reference to the task_struct.

Note: while_each_thread() under rcu_read_lock() is not really safe, it can
livelock.  This will be fixed later, but fortunately in this case the
"max_count" logic saves us anyway.
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarMandeep Singh Baines <msb@google.com>
Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6027ce49
    • Oleg Nesterov's avatar
      vfork: kill PF_STARTING · 6e27f63e
      Oleg Nesterov authored 
      Previously it was (ab)used by utrace.  Then it was wrongly used by the
scheduler code.

Currently it is not used, kill it before it finds the new erroneous user.
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6e27f63e
    • Oleg Nesterov's avatar
      coredump_wait: don't call complete_vfork_done() · 57b59c4a
      Oleg Nesterov authored 
      Now that CLONE_VFORK is killable, coredump_wait() no longer needs
complete_vfork_done().  zap_threads() should find and kill all tasks with
the same ->mm, this includes our parent if ->vfork_done is set.

mm_release() becomes the only caller, unexport complete_vfork_done().
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      57b59c4a
    • Oleg Nesterov's avatar
      vfork: make it killable · d68b46fe
      Oleg Nesterov authored 
      Make vfork() killable.

Change do_fork(CLONE_VFORK) to do wait_for_completion_killable().  If it
fails we do not return to the user-mode and never touch the memory shared
with our child.

However, in this case we should clear child->vfork_done before return, we
use task_lock() in do_fork()->wait_for_vfork_done() and
complete_vfork_done() to serialize with each other.

Note: now that we use task_lock() we don't really need completion, we
could turn task->vfork_done into "task_struct *wake_up_me" but this needs
some complications.

NOTE: this and the next patches do not affect in-kernel users of
CLONE_VFORK, kernel threads run with all signals ignored including
SIGKILL/SIGSTOP.

However this is obviously the user-visible change.  Not only a fatal
signal can kill the vforking parent, a sub-thread can do execve or
exit_group() and kill the thread sleeping in vfork().
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d68b46fe
    • Oleg Nesterov's avatar
      vfork: introduce complete_vfork_done() · c415c3b4
      Oleg Nesterov authored 
      No functional changes.

Move the clear-and-complete-vfork_done code into the new trivial helper,
complete_vfork_done().
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c415c3b4
    • Jeff Moyer's avatar
      aio: wake up waiters when freeing unused kiocbs · 880641bb
      Jeff Moyer authored 
      Bart Van Assche reported a hung fio process when either hot-removing
storage or when interrupting the fio process itself.  The (pruned) call
trace for the latter looks like so:

  fio             D 0000000000000001     0  6849   6848 0x00000004
   ffff880092541b88 0000000000000046 ffff880000000000 ffff88012fa11dc0
   ffff88012404be70 ffff880092541fd8 ffff880092541fd8 ffff880092541fd8
   ffff880128b894d0 ffff88012404be70 ffff880092541b88 000000018106f24d
  Call Trace:
    schedule+0x3f/0x60
    io_schedule+0x8f/0xd0
    wait_for_all_aios+0xc0/0x100
    exit_aio+0x55/0xc0
    mmput+0x2d/0x110
    exit_mm+0x10d/0x130
    do_exit+0x671/0x860
    do_group_exit+0x44/0xb0
    get_signal_to_deliver+0x218/0x5a0
    do_signal+0x65/0x700
    do_notify_resume+0x65/0x80
    int_signal+0x12/0x17

The problem lies with the allocation batching code.  It will
opportunistically allocate kiocbs, and then trim back the list of iocbs
when there is not enough room in the completion ring to hold all of the
events.

In the case above, what happens is that the pruning back of events ends
up freeing up the last active request and the context is marked as dead,
so it is thus responsible for waking up waiters.  Unfortunately, the
code does not check for this condition, so we end up with a hung task.
Signed-off-by: default avatarJeff Moyer <jmoyer@redhat.com>
Reported-by: default avatarBart Van Assche <bvanassche@acm.org>
Tested-by: default avatarBart Van Assche <bvanassche@acm.org>
Cc: <stable@kernel.org>		[3.2.x only]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      880641bb
    • Prashanth Nageshappa's avatar
      kprobes: return proper error code from register_kprobe() · f986a499
      Prashanth Nageshappa authored 
      register_kprobe() aborts if the address of the new request falls in a
prohibited area (such as ftrace pouch, __kprobes annotated functions,
non-kernel text addresses, jump label text).  We however don't return the
right error on this abort, resulting in a silent failure - incorrect
adding/reporting of kprobes ('perf probe do_fork+18' or 'perf probe
mcount' for instance).

In V2 we are incorporating Masami Hiramatsu's  feedback.

This patch fixes it by returning -EINVAL upon failure.

While we are here, rename the label used for exit to be more appropriate.
Signed-off-by: default avatarAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: default avatarPrashanth K Nageshappa <prashanth@linux.vnet.ibm.com>
Acked-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f986a499
    • Matthew Garrett's avatar
      kmsg_dump: don't run on non-error paths by default · c22ab332
      Matthew Garrett authored 
      Since commit 04c6862c ("kmsg_dump: add kmsg_dump() calls to the
reboot, halt, poweroff and emergency_restart paths"), kmsg_dump() gets
run on normal paths including poweroff and reboot.

This is less than ideal given pstore implementations that can only
represent single backtraces, since a reboot may overwrite a stored oops
before it's been picked up by userspace.  In addition, some pstore
backends may have low performance and provide a significant delay in
reboot as a result.

This patch adds a printk.always_kmsg_dump kernel parameter (which can also
be changed from userspace).  Without it, the code will only be run on
failure paths rather than on normal paths.  The option can be enabled in
environments where there's a desire to attempt to audit whether or not a
reboot was cleanly requested or not.
Signed-off-by: default avatarMatthew Garrett <mjg@redhat.com>
Acked-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Cc: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Don Zickus <dzickus@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c22ab332
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