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/openbmc/linux/lib/
H A Dpercpu_counter.cdiff e2852ae825dba5ebc159788720baec1a28a57125 Tue Oct 26 16:23:05 CDT 2010 Tejun Heo <tj@kernel.org> percpu_counter: add debugobj support

All percpu counters are linked to a global list on initialization and
removed from it on destruction. The list is walked during CPU up/down.
If a percpu counter is freed without being properly destroyed, the system
will oops only on the next CPU up/down making it pretty nasty to track
down. This patch adds debugobj support for percpu counters so that such
problems can be found easily.

As percpu counters don't make sense on stack and can't be statically
initialized, debugobj support is pretty simple. It's initialized and
activated on counter initialization, and deactivatd and destroyed on
counter destruction. With this patch applied, the bug fixed by commit
602586a83b719df0fbd94196a1359ed35aeb2df3 (shmem: put_super must
percpu_counter_destroy) triggers the following warning on tmpfs unmount
and the system won't oops on the next cpu up/down operation.

------------[ cut here ]------------
WARNING: at lib/debugobjects.c:259 debug_print_object+0x5c/0x70()
Hardware name: Bochs
ODEBUG: free active (active state 0) object type: percpu_counter
Modules linked in:
Pid: 3999, comm: umount Not tainted 2.6.36-rc2-work+ #5
Call Trace:
[<ffffffff81083f7f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff81084076>] warn_slowpath_fmt+0x46/0x50
[<ffffffff813b45cc>] debug_print_object+0x5c/0x70
[<ffffffff813b50e5>] debug_check_no_obj_freed+0x125/0x210
[<ffffffff811577d3>] kfree+0xb3/0x2f0
[<ffffffff81132edd>] shmem_put_super+0x1d/0x30
[<ffffffff81162e96>] generic_shutdown_super+0x56/0xe0
[<ffffffff81162f86>] kill_anon_super+0x16/0x60
[<ffffffff81162ff7>] kill_litter_super+0x27/0x30
[<ffffffff81163295>] deactivate_locked_super+0x45/0x60
[<ffffffff81163cfa>] deactivate_super+0x4a/0x70
[<ffffffff8117d446>] mntput_no_expire+0x86/0xe0
[<ffffffff8117df7f>] sys_umount+0x6f/0x360
[<ffffffff8103f01b>] system_call_fastpath+0x16/0x1b
---[ end trace cce2a341ba3611a7 ]---

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Thomas Gleixner <tglxlinutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
H A DKconfig.debugdiff e2852ae825dba5ebc159788720baec1a28a57125 Tue Oct 26 16:23:05 CDT 2010 Tejun Heo <tj@kernel.org> percpu_counter: add debugobj support

All percpu counters are linked to a global list on initialization and
removed from it on destruction. The list is walked during CPU up/down.
If a percpu counter is freed without being properly destroyed, the system
will oops only on the next CPU up/down making it pretty nasty to track
down. This patch adds debugobj support for percpu counters so that such
problems can be found easily.

As percpu counters don't make sense on stack and can't be statically
initialized, debugobj support is pretty simple. It's initialized and
activated on counter initialization, and deactivatd and destroyed on
counter destruction. With this patch applied, the bug fixed by commit
602586a83b719df0fbd94196a1359ed35aeb2df3 (shmem: put_super must
percpu_counter_destroy) triggers the following warning on tmpfs unmount
and the system won't oops on the next cpu up/down operation.

------------[ cut here ]------------
WARNING: at lib/debugobjects.c:259 debug_print_object+0x5c/0x70()
Hardware name: Bochs
ODEBUG: free active (active state 0) object type: percpu_counter
Modules linked in:
Pid: 3999, comm: umount Not tainted 2.6.36-rc2-work+ #5
Call Trace:
[<ffffffff81083f7f>] warn_slowpath_common+0x7f/0xc0
[<ffffffff81084076>] warn_slowpath_fmt+0x46/0x50
[<ffffffff813b45cc>] debug_print_object+0x5c/0x70
[<ffffffff813b50e5>] debug_check_no_obj_freed+0x125/0x210
[<ffffffff811577d3>] kfree+0xb3/0x2f0
[<ffffffff81132edd>] shmem_put_super+0x1d/0x30
[<ffffffff81162e96>] generic_shutdown_super+0x56/0xe0
[<ffffffff81162f86>] kill_anon_super+0x16/0x60
[<ffffffff81162ff7>] kill_litter_super+0x27/0x30
[<ffffffff81163295>] deactivate_locked_super+0x45/0x60
[<ffffffff81163cfa>] deactivate_super+0x4a/0x70
[<ffffffff8117d446>] mntput_no_expire+0x86/0xe0
[<ffffffff8117df7f>] sys_umount+0x6f/0x360
[<ffffffff8103f01b>] system_call_fastpath+0x16/0x1b
---[ end trace cce2a341ba3611a7 ]---

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Thomas Gleixner <tglxlinutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/openbmc/linux/mm/
H A Dshmem.cdiff 602586a83b719df0fbd94196a1359ed35aeb2df3 Tue Aug 17 17:23:56 CDT 2010 Hugh Dickins <hughd@google.com> shmem: put_super must percpu_counter_destroy

list_add() corruption messages reported from shmem_fill_super()'s recently
introduced percpu_counter_init(): shmem_put_super() needs to remember to
percpu_counter_destroy(). And also check error from percpu_counter_init().

Reported-bisected-and-tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>