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Date: Wed, 11 Apr 2018 02:38:37 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: Re: WARNING in kill_block_super
Message-ID: <20180411013836.GO30522@ZenIV.linux.org.uk>
References: <6c95e826-4b9f-fb21-b311-830411e58480@I-love.SAKURA.ne.jp>
 <20180411005938.GN30522@ZenIV.linux.org.uk>
 <201804110128.w3B1S6M6092645@www262.sakura.ne.jp>
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To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Michal Hocko <mhocko@suse.com>, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, linux-mm <linux-mm@kvack.org>, Dmitry Vyukov <dvyukov@google.com>, syzbot <syzbot+5a170e19c963a2e0df79@syzkaller.appspotmail.com>

On Wed, Apr 11, 2018 at 10:28:06AM +0900, Tetsuo Handa wrote:
> Al Viro wrote:
> > On Wed, Apr 04, 2018 at 07:53:07PM +0900, Tetsuo Handa wrote:
> > > Al and Michal, are you OK with this patch?
> > 
> > First of all, it does *NOT* fix the problems with careless ->kill_sb().
> > The fuse-blk case is the only real rationale so far.  Said that,
> > 
> 
> Please notice below one as well. Fixing all careless ->kill_sb() will be too
> difficult to backport. For now, avoid calling deactivate_locked_super() is
> safer.

How will that fix e.g. jffs2?

> [upstream] WARNING: refcount bug in put_pid_ns
> https://syzkaller.appspot.com/bug?id=17e202b4794da213570ba33ac2f70277ef1ce015

Should be fixed by 8e666cb33597 in that series, AFAICS.