linux-kernel - Re: [PATCH 4.14 0/2] Fix FUSE read/write deadlock on stream-like files

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Message-Id: <20190609171020.GA27685@deco.navytux.spb.ru>
Date:   Sun, 09 Jun 2019 17:10:28 +0000
From:   Kirill Smelkov <kirr@...edi.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     <stable@...r.kernel.org>, Sasha Levin <sashal@...nel.org>,
        Ben Hutchings <ben@...adent.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.14 0/2] Fix FUSE read/write deadlock on stream-like files

On Sun, Jun 09, 2019 at 06:38:26PM +0200, Greg KH wrote:
> On Sun, Jun 09, 2019 at 12:39:08PM +0000, Kirill Smelkov wrote:
> > Hello stable team,
> > 
> > Please consider applying the following 2 patches to Linux-4.14 stable
> > tree. The patches fix regression introduced in 3.14 where both read and
> > write started to run under lock taken, which resulted in FUSE (and many
> > other drivers) deadlocks for cases where stream-like files are used with
> > read and write being run simultaneously.
> > 
> > Please see complete problem description in upstream commit 10dce8af3422
> > ("fs: stream_open - opener for stream-like files so that read and write
> > can run simultaneously without deadlock").
> > 
> > The actual FUSE fix (upstream commit bbd84f33652f "fuse: Add
> > FOPEN_STREAM to use stream_open()") was merged into 5.2 with `Cc:
> > stable@...r.kernel.org # v3.14+` mark and is already included into 5.1,
> > 5.0 and 4.19 stable trees. However for some reason it is not (yet ?)
> > included into 4.14, 4.9, 4.4, 3.18 and 3.16 trees.
> > 
> > The patches fix a real problem into which my FUSE filesystem ran, and
> > which also likely affects OSSPD (full details are in the patches
> > description). Please consider including the fixes into 4.14 (as well as
> > into earlier stable trees - I will send corresponding series separately -
> > - one per tree).
> 
> Many thanks for these.  I've queued up all but the 3.16 patches (those
> are for Ben).
> 
> I hadn't done the backport yet, as I didn't know how "severe" this was,
> and didn't have the time to do it.  Thanks for making it easy :)

Greg, you are welcome and thanks a lot for feedback and for queueing the
patches. Ben, looking forward to 3.16 update to care about Jessie.

Thanks again,
Kirill