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slub: remove kmalloc under list_lock from list_slab_objects() V2

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list_slab_objects() is called when a slab is destroyed and there are
objects still left to list the objects in the syslog.  This is a pretty
rare event.

And there it seems we take the list_lock and call kmalloc while holding
that lock.

Perform the allocation in free_partial() before the list_lock is taken.

Fixes: bbd7d57bfe ("slub: Potential stack overflow")
Signed-off-by: Christopher Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yu Zhao <yuzhao@google.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2002031721250.1668@www.lameter.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Christopher Lameter 2020-06-01 21:45:53 -07:00 committed by Linus Torvalds
parent d7660ce591
commit aa456c7aeb
1 changed files with 15 additions and 5 deletions
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20
mm/slub.c
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@ -3766,12 +3766,14 @@ error:
}
static void list_slab_objects(struct kmem_cache *s, struct page *page,
const char *text)
const char *text, unsigned long *map)
{
#ifdef CONFIG_SLUB_DEBUG
void *addr = page_address(page);
void *p;
unsigned long *map;
if (!map)
return;
slab_err(s, page, text, s->name);
slab_lock(page);
@ -3784,8 +3786,6 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page,
print_tracking(s, p);
}
}
put_map(map);
slab_unlock(page);
#endif
}
@ -3799,6 +3799,11 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
LIST_HEAD(discard);
struct page *page, *h;
unsigned long *map = NULL;
#ifdef CONFIG_SLUB_DEBUG
map = bitmap_alloc(oo_objects(s->max), GFP_KERNEL);
#endif
BUG_ON(irqs_disabled());
spin_lock_irq(&n->list_lock);
@ -3808,11 +3813,16 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
list_add(&page->slab_list, &discard);
} else {
list_slab_objects(s, page,
"Objects remaining in %s on __kmem_cache_shutdown()");
"Objects remaining in %s on __kmem_cache_shutdown()",
map);
}
}
spin_unlock_irq(&n->list_lock);
#ifdef CONFIG_SLUB_DEBUG
bitmap_free(map);
#endif
list_for_each_entry_safe(page, h, &discard, slab_list)
discard_slab(s, page);
}