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

From: Robert Love
Date: Mon Jul 24 2006 - 18:06:45 EST

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@xxxxxxxxxxxxxxx>

Nice catch.

Signed-off-by: Robert Love <rml@xxxxxxxxxx>

Robert Love

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