From: Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx> 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. Signed-off-by: Michael Wang <wangyun@xxxxxxxxxxxxxxxxxx> --- mm/slab.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index d4715e5..cc679ef 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1780,9 +1780,6 @@ void __init kmem_cache_init_late(void) slab_state = UP; - /* Annotate slab for lockdep -- annotate the malloc caches */ - init_lock_keys(); - /* 6) resize the head arrays to their final sizes */ mutex_lock(&slab_mutex); list_for_each_entry(cachep, &slab_caches, list) @@ -1790,6 +1787,9 @@ void __init kmem_cache_init_late(void) BUG(); mutex_unlock(&slab_mutex); + /* Annotate slab for lockdep -- annotate the malloc caches */ + init_lock_keys(); + /* Done! */ slab_state = FULL; -- 1.7.4.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>