Re: netfilter: Hung task

On Mon, 19 Mar 2012, Sasha Levin wrote:

lockdep listed all the held locks there.

None of the locks listed are slub locks.

I've mentioned that it looks very similar to
https://lkml.org/lkml/2012/1/14/45 where the userspace helper tried to
read from the sysfs files, but got into a deadlock since the kernel
side held them before it called the usermode helper.

Ah yes. In that case slub held a semaphore. Code was changed since then to
no longer hold a semaphore when calling into sysfs.

The uevent handler can execute arbitrary user space code. Do you have to
hold locks while calling kmem_cache_destroy?