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Date: Wed, 31 Jan 2024 11:56:22 +0100
From: Christian Brauner <brauner@kernel.org>
To: Jan Kara <jack@suse.cz>
Cc: syzbot <syzbot+69b40dc5fd40f32c199f@syzkaller.appspotmail.com>, 
	akpm@linux-foundation.org, axboe@kernel.dk, chenzhongjin@huawei.com, dchinner@redhat.com, 
	hch@infradead.org, hch@lst.de, linux-fsdevel@vger.kernel.org, 
	linux-kernel@vger.kernel.org, penguin-kernel@i-love.sakura.ne.jp, 
	syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, willy@infradead.org
Subject: Re: [syzbot] [fs?] BUG: sleeping function called from invalid
 context in __getblk_gfp
Message-ID: <20240131-tapeziert-lustvoll-780b450e52c4@brauner>
References: <0000000000000ccf9a05ee84f5b0@google.com>
 <0000000000000d130006101f7e0e@google.com>
 <20240130115430.rljjwjcji3vlrgyz@quack3>
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On Tue, Jan 30, 2024 at 12:54:30PM +0100, Jan Kara wrote:
> On Mon 29-01-24 17:15:05, syzbot wrote:
> > syzbot suspects this issue was fixed by commit:
> > 
> > commit 6f861765464f43a71462d52026fbddfc858239a5
> > Author: Jan Kara <jack@suse.cz>
> > Date:   Wed Nov 1 17:43:10 2023 +0000
> > 
> >     fs: Block writes to mounted block devices
> > 
> > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=116642dfe80000
> > start commit:   d88520ad73b7 Merge tag 'pull-nfsd-fix' of git://git.kernel..
> > git tree:       upstream
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=174a257c5ae6b4fd
> > dashboard link: https://syzkaller.appspot.com/bug?extid=69b40dc5fd40f32c199f
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16a77593680000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1104a593680000
> > 
> > If the result looks correct, please mark the issue as fixed by replying with:
> > 
> > #syz fix: fs: Block writes to mounted block devices
> 
> This doesn't look correct. The problem here really is that sysv is calling
> sb_bread() under a RWLOCK - pointers_lock - in get_block(). Which more or
> less shows nobody has run sysv in ages because otherwise the chances of
> sleeping in atomic context are really high? Perhaps another candidate for
> removal?

Fwiw, yes, please!