| From 947ca1856a7e60aa6d20536785e6a42dff25aa6e Mon Sep 17 00:00:00 2001 |
| From: Michael Wang <wangyun@linux.vnet.ibm.com> |
| Date: Wed, 5 Sep 2012 10:33:18 +0800 |
| Subject: slab: fix the DEADLOCK issue on l3 alien lock |
| |
| 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; |
| |