On Tue, Jan 17, 2012 at 5:30 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
> Le mardi 17 janvier 2012 à 09:27 -0600, Christoph Lameter a écrit :
>
>> Subject: slub: Do not hold slub_lock when calling sysfs_slab_add()
>>
>> sysfs_slab_add() calls various sysfs functions that actually may
>> end up in userspace doing all sorts of things.
>>
>> Release the slub_lock after adding the kmem_cache structure to the list.
>> At that point the address of the kmem_cache is not known so we are
>> guaranteed exlusive access to the following modifications to the
>> kmem_cache structure.
>>
>> If the sysfs_slab_add fails then reacquire the slub_lock to
>> remove the kmem_cache structure from the list.
>>
>> Reported-by: Sasha Levin <levinsasha928@xxxxxxxxx>
>> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
>>
>> ---
>> mm/slub.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> Index: linux-2.6/mm/slub.c
>> ===================================================================
>> --- linux-2.6.orig/mm/slub.c 2012-01-17 03:07:11.140010438 -0600
>> +++ linux-2.6/mm/slub.c 2012-01-17 03:26:06.799986908 -0600
>> @@ -3929,13 +3929,14 @@ struct kmem_cache *kmem_cache_create(con
>> if (kmem_cache_open(s, n,
>> size, align, flags, ctor)) {
>> list_add(&s->list, &slab_caches);
>> + up_write(&slub_lock);
>> if (sysfs_slab_add(s)) {
>> + down_write(&slub_lock);
>> list_del(&s->list);
>> kfree(n);
>> kfree(s);
>> goto err;
>> }
>> - up_write(&slub_lock);
>> return s;
>> }
>> kfree(n);
>
> Thanks !
>
> Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
I'm planning to queue this for v3.4 and tagging it for -stable for
v3.3. Do we need this for older versions as well?
Pekka
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