Commit 8bdec192 authored by Rafael Aquini's avatar Rafael Aquini Committed by Pekka Enberg
Browse files

mm: SLAB Out-of-memory diagnostics 



Following the example at mm/slub.c, add out-of-memory diagnostics to the
SLAB allocator to help on debugging certain OOM conditions.

An example print out looks like this:

  <snip page allocator out-of-memory message>
  SLAB: Unable to allocate memory on node 0 (gfp=0x11200)
    cache: bio-0, object size: 192, order: 0
    node 0: slabs: 3/3, objs: 60/60, free: 0

Signed-off-by: default avatarRafael Aquini <aquini@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent a8203725

mm/slab.c

+50 −1
Original line number Diff line number Diff line
@@ -1731,6 +1731,52 @@ static int __init cpucache_init(void) 
}

__initcall(cpucache_init);



static noinline void

slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)

{

	struct kmem_list3 *l3;

	struct slab *slabp;

	unsigned long flags;

	int node;



	printk(KERN_WARNING

		"SLAB: Unable to allocate memory on node %d (gfp=0x%x)\n",

		nodeid, gfpflags);

	printk(KERN_WARNING "  cache: %s, object size: %d, order: %d\n",

		cachep->name, cachep->buffer_size, cachep->gfporder);



	for_each_online_node(node) {

		unsigned long active_objs = 0, num_objs = 0, free_objects = 0;

		unsigned long active_slabs = 0, num_slabs = 0;



		l3 = cachep->nodelists[node];

		if (!l3)

			continue;



		spin_lock_irqsave(&l3->list_lock, flags);

		list_for_each_entry(slabp, &l3->slabs_full, list) {

			active_objs += cachep->num;

			active_slabs++;

		}

		list_for_each_entry(slabp, &l3->slabs_partial, list) {

			active_objs += slabp->inuse;

			active_slabs++;

		}

		list_for_each_entry(slabp, &l3->slabs_free, list)

			num_slabs++;



		free_objects += l3->free_objects;

		spin_unlock_irqrestore(&l3->list_lock, flags);



		num_slabs += active_slabs;

		num_objs = num_slabs * cachep->num;

		printk(KERN_WARNING

			"  node %d: slabs: %ld/%ld, objs: %ld/%ld, free: %ld\n",

			node, active_slabs, num_slabs, active_objs, num_objs,

			free_objects);

	}

}



/*

 * Interface to system's page allocator. No need to hold the cache-lock.

 *
@@ -1757,8 +1803,11 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid) 
		flags |= __GFP_RECLAIMABLE;



	page = alloc_pages_exact_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder);

	if (!page)

	if (!page) {

		if (!(flags & __GFP_NOWARN) && printk_ratelimit())

			slab_out_of_memory(cachep, flags, nodeid);

		return NULL;

	}



	nr_pages = (1 << cachep->gfporder);

	if (cachep->flags & SLAB_RECLAIM_ACCOUNT)

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