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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>
This commit is contained in:
Pekka Enberg 2009-06-10 18:50:32 +03:00
parent 59a3759d0f
commit 781b2ba6eb
1 changed files with 51 additions and 19 deletions
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70
mm/slub.c
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@ -1484,6 +1484,56 @@ static inline int node_match(struct kmem_cache_cpu *c, int node)
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 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
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 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
}
#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 @@ static int count_total(struct page *page)
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)
{