| From | Greg Kroah-Hartman <> | Subject | [ 004/120] slab: fix the DEADLOCK issue on l3 alien lock | Date | Thu, 11 Oct 2012 09:59:16 +0900 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Michael Wang <wangyun@linux.vnet.ibm.com>
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>
--- mm/slab.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- 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 */ mutex_lock(&cache_chain_mutex); list_for_each_entry(cachep, &cache_chain, next) @@ -1695,6 +1692,9 @@ void __init kmem_cache_init_late(void) BUG(); mutex_unlock(&cache_chain_mutex); + /* Annotate slab for lockdep -- annotate the malloc caches */ + init_lock_keys(); + /* Done! */ g_cpucache_up = FULL;
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