path: root/mm
diff options
authorMichael Wang <wangyun@linux.vnet.ibm.com>2012-09-05 10:33:18 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-13 05:38:37 +0900
commit750025ab1950b5e32e308c446de32c399cf2d6f6 (patch)
tree4c3abc9b042fae866b187b2b69810585d9cd1be8 /mm
parent4893cf612a68d26cdbe0e16ba9c42772136e2340 (diff)
slab: fix the DEADLOCK issue on l3 alien lock
commit 947ca1856a7e60aa6d20536785e6a42dff25aa6e upstream. 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. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/slab.c b/mm/slab.c
index e901a36e2520..da2bb689a008 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1685,9 +1685,6 @@ void __init kmem_cache_init_late(void)
g_cpucache_up = LATE;
- /* Annotate slab for lockdep -- annotate the malloc caches */
- init_lock_keys();
/* 6) resize the head arrays to their final sizes */
list_for_each_entry(cachep, &cache_chain, next)
@@ -1695,6 +1692,9 @@ void __init kmem_cache_init_late(void)
+ /* Annotate slab for lockdep -- annotate the malloc caches */
+ init_lock_keys();
/* Done! */
g_cpucache_up = FULL;