[PATCH] slub: fix slab_pad_check()

From: Eric Dumazet
Date: Thu Sep 03 2009 - 10:11:41 EST

Christoph Lameter a écrit :
> On Thu, 3 Sep 2009, Eric Dumazet wrote:
>> on a SLAB_DESTROY_BY_RCU cache, there is no need to try to optimize this
>> rcu_barrier() call, unless we want superfast reboot/halt sequences...
> I stilll think that the action to quiesce rcu is something that the caller
> of kmem_cache_destroy must take care of.

Do you mean :

if (kmem_cache_shrink(s) == 0) {
} else {

What would be the point ?

> Could you split this into two patches: One that addresses the poison and
> another that deals with rcu?

Sure, here is the poison thing

[PATCH] slub: fix slab_pad_check()

When SLAB_POISON is used and slab_pad_check() finds an overwrite of the
slab padding, we call restore_bytes() on the whole slab, not only
on the padding.

Reported-by: Zdenek Kabelac <zdenek.kabelac@xxxxxxxxx>
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
diff --git a/mm/slub.c b/mm/slub.c
index b9f1491..0ac839f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -646,7 +646,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
print_section("Padding", end - remainder, remainder);

- restore_bytes(s, "slab padding", POISON_INUSE, start, end);
+ restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
return 0;

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