From: Cong Wang <[email protected]>
Date: Thu, 17 Nov 2016 15:55:26 -0800
> Commit 2b15af6f95 ("af_unix: use freezable blocking calls in read")
> converts schedule_timeout() to its freezable version, it was probably
> correct at that time, but later, commit 2b514574f7e8
> ("net: af_unix: implement splice for stream af_unix sockets") breaks
> the strong requirement for a freezable sleep, according to
> commit 0f9548ca1091:
>
> We shouldn't try_to_freeze if locks are held. Holding a lock can cause a
> deadlock if the lock is later acquired in the suspend or hibernate path
> (e.g. by dpm). Holding a lock can also cause a deadlock in the case of
> cgroup_freezer if a lock is held inside a frozen cgroup that is later
> acquired by a process outside that group.
>
> The pipe_lock is still held at that point.
>
> So use freezable version only for the recvmsg call path, avoid impact for
> Android.
>
> Fixes: 2b514574f7e8 ("net: af_unix: implement splice for stream af_unix
> sockets")
> Reported-by: Dmitry Vyukov <[email protected]>
> Cc: Tejun Heo <[email protected]>
> Cc: Colin Cross <[email protected]>
> Cc: Rafael J. Wysocki <[email protected]>
> Cc: Hannes Frederic Sowa <[email protected]>
> Signed-off-by: Cong Wang <[email protected]>
Applied and queued up for -stable, thanks.
