diff options
author | Michael Wang <wangyun@linux.vnet.ibm.com> | 2012-09-04 22:33:18 -0400 |
---|---|---|
committer | Pekka Enberg <penberg@kernel.org> | 2012-09-11 12:29:18 -0400 |
commit | 947ca1856a7e60aa6d20536785e6a42dff25aa6e (patch) | |
tree | de1ee6cafeeb7e95205f4ede7e55b89565f95cd7 /mm/slab.c | |
parent | e21827aadd77e33833eeb393de2e8675e9b399e2 (diff) |
slab: fix the DEADLOCK issue on l3 alien lock
DEADLOCK will be report while running a kernel with NUMA and LOCKDEP enabled,
the process of this fake report is:
kmem_cache_free() //free obj in cachep
-> cache_free_alien() //acquire cachep's l3 alien lock
-> __drain_alien_cache()
-> free_block()
-> slab_destroy()
-> kmem_cache_free() //free slab in cachep->slabp_cache
-> cache_free_alien() //acquire cachep->slabp_cache's l3 alien lock
Since the cachep and cachep->slabp_cache's l3 alien are in the same lock class,
fake report generated.
This should not happen since we already have init_lock_keys() which will
reassign the lock class for both l3 list and l3 alien.
However, init_lock_keys() was invoked at a wrong position which is before we
invoke enable_cpucache() on each cache.
Since until set slab_state to be FULL, we won't invoke enable_cpucache()
on caches to build their l3 alien while creating them, so although we invoked
init_lock_keys(), the l3 alien lock class won't change since we don't have
them until invoked enable_cpucache() later.
This patch will invoke init_lock_keys() after we done enable_cpucache()
instead of before to avoid the fake DEADLOCK report.
Michael traced the problem back to a commit in release 3.0.0:
commit 30765b92ada267c5395fc788623cb15233276f5c
Author: Peter Zijlstra <peterz@infradead.org>
Date: Thu Jul 28 23:22:56 2011 +0200
slab, lockdep: Annotate the locks before using them
Fernando found we hit the regular OFF_SLAB 'recursion' before we
annotate the locks, cure this.
The relevant portion of the stack-trace:
> [ 0.000000] [<c085e24f>] rt_spin_lock+0x50/0x56
> [ 0.000000] [<c04fb406>] __cache_free+0x43/0xc3
> [ 0.000000] [<c04fb23f>] kmem_cache_free+0x6c/0xdc
> [ 0.000000] [<c04fb2fe>] slab_destroy+0x4f/0x53
> [ 0.000000] [<c04fb396>] free_block+0x94/0xc1
> [ 0.000000] [<c04fc551>] do_tune_cpucache+0x10b/0x2bb
> [ 0.000000] [<c04fc8dc>] enable_cpucache+0x7b/0xa7
> [ 0.000000] [<c0bd9d3c>] kmem_cache_init_late+0x1f/0x61
> [ 0.000000] [<c0bba687>] start_kernel+0x24c/0x363
> [ 0.000000] [<c0bba0ba>] i386_start_kernel+0xa9/0xaf
Reported-by: Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>
Acked-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1311888176.2617.379.camel@laptop
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The commit moved init_lock_keys() before we build up the alien, so we
failed to reclass it.
Cc: <stable@vger.kernel.org> # 3.0+
Acked-by: Christoph Lameter <cl@linux.com>
Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'mm/slab.c')
-rw-r--r-- | mm/slab.c | 6 |
1 files changed, 3 insertions, 3 deletions
@@ -1774,9 +1774,6 @@ void __init kmem_cache_init_late(void) | |||
1774 | 1774 | ||
1775 | slab_state = UP; | 1775 | slab_state = UP; |
1776 | 1776 | ||
1777 | /* Annotate slab for lockdep -- annotate the malloc caches */ | ||
1778 | init_lock_keys(); | ||
1779 | |||
1780 | /* 6) resize the head arrays to their final sizes */ | 1777 | /* 6) resize the head arrays to their final sizes */ |
1781 | mutex_lock(&slab_mutex); | 1778 | mutex_lock(&slab_mutex); |
1782 | list_for_each_entry(cachep, &slab_caches, list) | 1779 | list_for_each_entry(cachep, &slab_caches, list) |
@@ -1784,6 +1781,9 @@ void __init kmem_cache_init_late(void) | |||
1784 | BUG(); | 1781 | BUG(); |
1785 | mutex_unlock(&slab_mutex); | 1782 | mutex_unlock(&slab_mutex); |
1786 | 1783 | ||
1784 | /* Annotate slab for lockdep -- annotate the malloc caches */ | ||
1785 | init_lock_keys(); | ||
1786 | |||
1787 | /* Done! */ | 1787 | /* Done! */ |
1788 | slab_state = FULL; | 1788 | slab_state = FULL; |
1789 | 1789 | ||