Messages in this thread Patch in this message | | | Date | Thu, 03 Sep 2009 03:04:32 +0200 | From | Eric Dumazet <> | Subject | [PATCH] slub: fix slab_pad_check() and SLAB_DESTROY_BY_RCU |
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Zdenek Kabelac a écrit : > > Well I'm not noticing any ill behavior - also note - rcu_barrier() is > there before the cache is destroyed. > But as I said - it's just my shot into the dark - which seems to work for me... >
Reading again your traces, I do believe there are two bugs in slub
Maybe not explaining your problem, but worth to fix !
Thank you
[PATCH] slub: fix slab_pad_check() and SLAB_DESTROY_BY_RCU
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.
kmem_cache_destroy() should call rcu_barrier() *after* kmem_cache_close() and *before* sysfs_slab_remove() or risk rcu_free_slab() being called after kmem_cache is deleted (kfreed).
rmmod nf_conntrack can crash the machine because it has to kmem_cache_destroy() a SLAB_DESTROY_BY_RCU enabled cache.
Reported-by: Zdenek Kabelac <zdenek.kabelac@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> --- 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; } @@ -2594,8 +2594,6 @@ static inline int kmem_cache_close(struct kmem_cache *s) */ void kmem_cache_destroy(struct kmem_cache *s) { - if (s->flags & SLAB_DESTROY_BY_RCU) - rcu_barrier(); down_write(&slub_lock); s->refcount--; if (!s->refcount) { @@ -2606,6 +2604,8 @@ void kmem_cache_destroy(struct kmem_cache *s) "still has objects.\n", s->name, __func__); dump_stack(); } + if (s->flags & SLAB_DESTROY_BY_RCU) + rcu_barrier(); sysfs_slab_remove(s); } else up_write(&slub_lock); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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