From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 6 Jul 2007 12:52:25 -0700 (PDT) From: Christoph Lameter Subject: SLUB: Do not allocate object bit array on stack Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: akpm@linux-foundation.org Cc: linux-mm@kvack.org List-ID: 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: Christoph Lameter --- mm/slub.c | 39 +++++++++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 14 deletions(-) Index: linux-2.6.22-rc6-mm1/mm/slub.c =================================================================== --- linux-2.6.22-rc6-mm1.orig/mm/slub.c 2007-07-04 13:37:41.000000000 -0700 +++ linux-2.6.22-rc6-mm1/mm/slub.c 2007-07-04 13:38:51.000000000 -0700 @@ -2784,11 +2784,11 @@ void *__kmalloc_node_track_caller(size_t } #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)) @@ -2810,10 +2810,11 @@ static int validate_slab(struct kmem_cac 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", @@ -2830,7 +2831,8 @@ static void validate_slab_slab(struct km } } -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; @@ -2839,7 +2841,7 @@ static int validate_slab_node(struct kme 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) @@ -2850,7 +2852,7 @@ static int validate_slab_node(struct kme 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)) @@ -2863,17 +2865,23 @@ 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; } @@ -3487,11 +3495,14 @@ static ssize_t validate_show(struct kmem 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); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org