The patch titled
Subject: slub: remove kmalloc under list_lock from list_slab_objects() V2
has been added to the -mm tree. Its filename is
slub-remove-kmalloc-under-list_lock-from-list_slab_objects.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/slub-remove-kmalloc-under-list_lock-from-list_slab_objects.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/slub-remove-kmalloc-under-list_lock-from-list_slab_objects.patch
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The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Christopher Lameter <cl@xxxxxxxxx>
Subject: slub: remove kmalloc under list_lock from list_slab_objects() V2
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.
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2002031721250.1668@xxxxxxxxxxxxxxx
Fixes: bbd7d57bfe852d9788bae5fb171c7edb4021d8ac ("slub: Potential stack overflow")
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
--- a/mm/slub.c~slub-remove-kmalloc-under-list_lock-from-list_slab_objects
+++ a/mm/slub.c
@@ -3751,12 +3751,14 @@ 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);
@@ -3769,8 +3771,6 @@ static void list_slab_objects(struct kme
print_tracking(s, p);
}
}
- put_map(map);
-
slab_unlock(page);
#endif
}
@@ -3784,6 +3784,11 @@ static void free_partial(struct kmem_cac
{
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);
@@ -3793,11 +3798,16 @@ static void free_partial(struct kmem_cac
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);
}
_
Patches currently in -mm which might be from cl@xxxxxxxxx are
slub-remove-userspace-notifier-for-cache-add-remove.patch
slub-remove-kmalloc-under-list_lock-from-list_slab_objects.patch
