From: Miklos Szeredi Subject: [PATCH 30/31] Fix use of uninitialized variable in cache_grow() Patch-mainline: not yet This fixes a bug in reserve-slub.patch. If cache_grow() was called with objp != NULL then the 'reserve' local variable wasn't initialized. This resulted in ac->reserve being set to a rubbish value. Due to this in some circumstances huge amounts of slab pages were allocated (due to slab_force_alloc() returning true), which caused atomic page allocation failures and slowdown of the system. Signed-off-by: Miklos Szeredi Signed-off-by: Suresh Jayaraman --- mm/slab.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/slab.c +++ b/mm/slab.c @@ -2773,7 +2773,7 @@ static int cache_grow(struct kmem_cache size_t offset; gfp_t local_flags; struct kmem_list3 *l3; - int reserve; + int reserve = -1; /* * Be lazy and only check for valid flags here, keeping it out of the @@ -2829,7 +2829,8 @@ static int cache_grow(struct kmem_cache if (local_flags & __GFP_WAIT) local_irq_disable(); check_irq_off(); - slab_set_reserve(cachep, reserve); + if (reserve != -1) + slab_set_reserve(cachep, reserve); spin_lock(&l3->list_lock); /* Make slab active. */