Re: netfilter: Hung task

From: Christoph Lameter
Date: Mon Mar 19 2012 - 16:03:18 EST


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?


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