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: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slub.c b/mm/slub.c
index 510ee9a..f976d28 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2764,11 +2764,11 @@
}
#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 @@
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 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 @@
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 @@
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 @@
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_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);
