3.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael Wang <wang...@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 <pet...@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 <na...@ccrma.stanford.edu>
Acked-by: Pekka Enberg <penb...@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijls...@chello.nl>
Link: http://lkml.kernel.org/r/1311888176.2617.379.camel@laptop
Signed-off-by: Ingo Molnar <mi...@elte.hu>
The commit moved init_lock_keys() before we build up the alien, so we
failed to reclass it.
Acked-by: Christoph Lameter <c...@linux.com>
Tested-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Signed-off-by: Michael Wang <wang...@linux.vnet.ibm.com>
Signed-off-by: Pekka Enberg <penb...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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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