SLUB: Out-of-memory diagnostics
As suggested by Mel Gorman, add out-of-memory diagnostics to the SLUB allocator
to make debugging OOM conditions easier. This patch helped hunt down a nasty
OOM issue that popped up every now that was caused by SLUB debugging code which
forced 4096 byte allocations to use order 1 pages even in the fallback case.
An example print out looks like this:
<snip page allocator out-of-memory message>
SLUB: Unable to allocate memory on node -1 (gfp=20)
cache: kmalloc-4096, object size: 4096, buffer size: 4168, default order: 3, min order: 1
node 0: slabs: 95, objs: 665, free: 0
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/slub.c b/mm/slub.c
index 65ffda5..a5a4ecf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1484,6 +1484,56 @@
return 1;
}
+static int count_free(struct page *page)
+{
+ return page->objects - page->inuse;
+}
+
+static unsigned long count_partial(struct kmem_cache_node *n,
+ int (*get_count)(struct page *))
+{
+ unsigned long flags;
+ unsigned long x = 0;
+ struct page *page;
+
+ spin_lock_irqsave(&n->list_lock, flags);
+ list_for_each_entry(page, &n->partial, lru)
+ x += get_count(page);
+ spin_unlock_irqrestore(&n->list_lock, flags);
+ return x;
+}
+
+static noinline void
+slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
+{
+ int node;
+
+ printk(KERN_WARNING
+ "SLUB: Unable to allocate memory on node %d (gfp=0x%x)\n",
+ nid, gfpflags);
+ printk(KERN_WARNING " cache: %s, object size: %d, buffer size: %d, "
+ "default order: %d, min order: %d\n", s->name, s->objsize,
+ s->size, oo_order(s->oo), oo_order(s->min));
+
+ for_each_online_node(node) {
+ struct kmem_cache_node *n = get_node(s, node);
+ unsigned long nr_slabs;
+ unsigned long nr_objs;
+ unsigned long nr_free;
+
+ if (!n)
+ continue;
+
+ nr_slabs = atomic_long_read(&n->nr_slabs);
+ nr_objs = atomic_long_read(&n->total_objects);
+ nr_free = count_partial(n, count_free);
+
+ printk(KERN_WARNING
+ " node %d: slabs: %ld, objs: %ld, free: %ld\n",
+ node, nr_slabs, nr_objs, nr_free);
+ }
+}
+
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
@@ -1565,6 +1615,7 @@
c->page = new;
goto load_freelist;
}
+ slab_out_of_memory(s, gfpflags, node);
return NULL;
debug:
if (!alloc_debug_processing(s, c->page, object, addr))
@@ -3318,20 +3369,6 @@
}
#ifdef CONFIG_SLUB_DEBUG
-static unsigned long count_partial(struct kmem_cache_node *n,
- int (*get_count)(struct page *))
-{
- unsigned long flags;
- unsigned long x = 0;
- struct page *page;
-
- spin_lock_irqsave(&n->list_lock, flags);
- list_for_each_entry(page, &n->partial, lru)
- x += get_count(page);
- spin_unlock_irqrestore(&n->list_lock, flags);
- return x;
-}
-
static int count_inuse(struct page *page)
{
return page->inuse;
@@ -3342,11 +3379,6 @@
return page->objects;
}
-static int count_free(struct page *page)
-{
- return page->objects - page->inuse;
-}
-
static int validate_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
{