From: Joe Korty Date: Wed, 5 Mar 2008 23:04:59 +0000 (-0800) Subject: slab: NUMA slab allocator migration bugfix X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=6d2144d355d2a532e5cc3fc12a6ba2a8d4ef15e4;p=openwrt%2Fstaging%2Fblogic.git slab: NUMA slab allocator migration bugfix NUMA slab allocator cpu migration bugfix The NUMA slab allocator (specifically, cache_alloc_refill) is not refreshing its local copies of what cpu and what numa node it is on, when it drops and reacquires the irq block that it inherited from its caller. As a result those values become invalid if an attempt to migrate the process to another numa node occured while the irq block had been dropped. The solution is to make cache_alloc_refill reload these variables whenever it drops and reacquires the irq block. The error is very difficult to hit. When it does occur, one gets the following oops + stack traceback bits in check_spinlock_acquired: kernel BUG at mm/slab.c:2417 cache_alloc_refill+0xe6 kmem_cache_alloc+0xd0 ... This patch was developed against 2.6.23, ported to and compiled-tested only against 2.6.25-rc4. Signed-off-by: Joe Korty Signed-off-by: Christoph Lameter --- diff --git a/mm/slab.c b/mm/slab.c index f7faff72cf56..e6c698f55674 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2964,11 +2964,10 @@ static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags) struct array_cache *ac; int node; - node = numa_node_id(); - +retry: check_irq_off(); + node = numa_node_id(); ac = cpu_cache_get(cachep); -retry: batchcount = ac->batchcount; if (!ac->touched && batchcount > BATCHREFILL_LIMIT) { /*