This is a note to let you know that I've just added the patch titled netfilter: ipset: Fix sleeping memory allocation in atomic context to the 4.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: netfilter-ipset-fix-sleeping-memory-allocation-in-atomic-context.patch and it can be found in the queue-4.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 00db674bedd68ff8b5afae9030ff5e04d45d1b4a Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <kernel@xxxxxxxx> Date: Fri, 16 Oct 2015 09:40:28 +0300 Subject: netfilter: ipset: Fix sleeping memory allocation in atomic context From: Nikolay Borisov <kernel@xxxxxxxx> commit 00db674bedd68ff8b5afae9030ff5e04d45d1b4a upstream. Commit 00590fdd5be0 introduced RCU locking in list type and in doing so introduced a memory allocation in list_set_add, which is done in an atomic context, due to the fact that ipset rcu list modifications are serialised with a spin lock. The reason why we can't use a mutex is that in addition to modifying the list with ipset commands, it's also being modified when a particular ipset rule timeout expires aka garbage collection. This gc is triggered from set_cleanup_entries, which in turn is invoked from a timer thus requiring the lock to be bh-safe. Concretely the following call chain can lead to "sleeping function called in atomic context" splat: call_ad -> list_set_uadt -> list_set_uadd -> kzalloc(, GFP_KERNEL). And since GFP_KERNEL allows initiating direct reclaim thus potentially sleeping in the allocation path. To fix the issue change the allocation type to GFP_ATOMIC, to correctly reflect that it is occuring in an atomic context. Fixes: 00590fdd5be0 ("netfilter: ipset: Introduce RCU locking in list type") Signed-off-by: Nikolay Borisov <kernel@xxxxxxxx> Acked-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/netfilter/ipset/ip_set_list_set.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/netfilter/ipset/ip_set_list_set.c +++ b/net/netfilter/ipset/ip_set_list_set.c @@ -297,7 +297,7 @@ list_set_uadd(struct ip_set *set, void * ip_set_timeout_expired(ext_timeout(n, set)))) n = NULL; - e = kzalloc(set->dsize, GFP_KERNEL); + e = kzalloc(set->dsize, GFP_ATOMIC); if (!e) return -ENOMEM; e->id = d->id; Patches currently in stable-queue which might be from kernel@xxxxxxxx are queue-4.2/netfilter-ipset-fix-sleeping-memory-allocation-in-atomic-context.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html