Re: [patch] inotify: fix deadlock found by lockdep

Robert Love
2006-07-24T22:08:46Z

On Mon, 2006-07-24 at 19:21 +0200, Arjan van de Ven wrote:

> inotify_dev_queue_event schedules a kernel_event which does a
> kmem_cache_alloc( , GFP_KERNEL) which may try to shrink slabs, including
> the inode cache .. which then takes iprune_mutex.
>
> And voila, there is an AB, a BC, a CD relationship (even a direct BCD),
> and also now a DA relationship -> a circular type AB-BA deadlock but
> involving 4 locks.
>
> The solution is simple: kernel_event() is NOT allowed to use GFP_KERNEL,
> but must use GFP_NOFS to not cause recursion into the VFS.
>
> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

Nice catch.

Signed-off-by: Robert Love <rml@novell.com>

Robert Love