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Commit 434e245d authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
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SLUB: Do not allocate object bit array on stack 



The objects per slab increase with the current patches in mm since we allow up
to order 3 allocs by default.  More patches in mm actually allow to use 2M or
higher sized slabs.  For slab validation we need per object bitmaps in order
to check a slab.  We end up with up to 64k objects per slab resulting in a
potential requirement of 8K stack space.  That does not look good.

Allocate the bit arrays via kmalloc.

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 94f6030c

mm/slub.c

+25 −14
Original line number Diff line number Diff line
@@ -2764,11 +2764,11 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags, 
}



#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)

static int validate_slab(struct kmem_cache *s, struct page *page)

static int validate_slab(struct kmem_cache *s, struct page *page,

						unsigned long *map)

{

	void *p;

	void *addr = page_address(page);

	DECLARE_BITMAP(map, s->objects);



	if (!check_slab(s, page) ||

			!on_freelist(s, page, NULL))
@@ -2790,10 +2790,11 @@ static int validate_slab(struct kmem_cache *s, struct page *page) 
	return 1;

}



static void validate_slab_slab(struct kmem_cache *s, struct page *page)

static void validate_slab_slab(struct kmem_cache *s, struct page *page,

						unsigned long *map)

{

	if (slab_trylock(page)) {

		validate_slab(s, page);

		validate_slab(s, page, map);

		slab_unlock(page);

	} else

		printk(KERN_INFO "SLUB %s: Skipped busy slab 0x%p\n",
@@ -2810,7 +2811,8 @@ static void validate_slab_slab(struct kmem_cache *s, struct page *page) 
	}

}



static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n)

static int validate_slab_node(struct kmem_cache *s,

		struct kmem_cache_node *n, unsigned long *map)

{

	unsigned long count = 0;

	struct page *page;
@@ -2819,7 +2821,7 @@ static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n) 
	spin_lock_irqsave(&n->list_lock, flags);



	list_for_each_entry(page, &n->partial, lru) {

		validate_slab_slab(s, page);

		validate_slab_slab(s, page, map);

		count++;

	}

	if (count != n->nr_partial)
@@ -2830,7 +2832,7 @@ static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n) 
		goto out;



	list_for_each_entry(page, &n->full, lru) {

		validate_slab_slab(s, page);

		validate_slab_slab(s, page, map);

		count++;

	}

	if (count != atomic_long_read(&n->nr_slabs))
@@ -2843,17 +2845,23 @@ out: 
	return count;

}



static unsigned long validate_slab_cache(struct kmem_cache *s)

static long validate_slab_cache(struct kmem_cache *s)

{

	int node;

	unsigned long count = 0;

	unsigned long *map = kmalloc(BITS_TO_LONGS(s->objects) *

				sizeof(unsigned long), GFP_KERNEL);



	if (!map)

		return -ENOMEM;



	flush_all(s);

	for_each_online_node(node) {

		struct kmem_cache_node *n = get_node(s, node);



		count += validate_slab_node(s, n);

		count += validate_slab_node(s, n, map);

	}

	kfree(map);

	return count;

}
@@ -3467,11 +3475,14 @@ static ssize_t validate_show(struct kmem_cache *s, char *buf) 
static ssize_t validate_store(struct kmem_cache *s,

			const char *buf, size_t length)

{

	if (buf[0] == '1')

		validate_slab_cache(s);

	else

		return -EINVAL;

	return length;

	int ret = -EINVAL;



	if (buf[0] == '1') {

		ret = validate_slab_cache(s);

		if (ret >= 0)

			ret = length;

	}

	return ret;

}

SLAB_ATTR(validate);