mm, slab: lock the correct nodelist after reenabling irqs

cache_grow() can reenable irqs so the cpu (and node) can change, so ensure
that we take list_lock on the correct nodelist.

This fixes an issue with commit 072bb0aa ("mm: sl[au]b: add
knowledge of PFMEMALLOC reserve pages") where list_lock for the wrong
node was taken after growing the cache.
Reported-and-tested-by: NHaggai Eran <haggaie@mellanox.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/slab.c

@@ -3260,6 +3260,7 @@ static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags,
 
 		/* cache_grow can reenable interrupts, then ac could change. */
 		ac = cpu_cache_get(cachep);
+		node = numa_mem_id();
 
 		/* no objects in sight? abort */
 		if (!x && (ac->avail == 0 || force_refill))