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Date: Thu, 16 May 2024 16:35:43 +0200
From: David Sterba <dsterba@suse.cz>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Sterba <dsterba@suse.cz>,
	syzbot <syzbot+c92c93d1f1aaaacdb9db@syzkaller.appspotmail.com>,
	axboe@kernel.dk, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, maz@kernel.org, oleg@redhat.com,
	peterz@infradead.org, syzkaller-bugs@googlegroups.com
Subject: Re: kernel BUG at fs/inode.c:LINE! (2)
Message-ID: <20240516143543.GY4449@twin.jikos.cz>
Reply-To: dsterba@suse.cz
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 <20240515161314.GO4449@twin.jikos.cz>
 <20240515170054.GM2118490@ZenIV>
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User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12)

On Wed, May 15, 2024 at 06:00:54PM +0100, Al Viro wrote:
> On Wed, May 15, 2024 at 06:13:14PM +0200, David Sterba wrote:
> > On Fri, Aug 28, 2020 at 06:18:17AM -0700, syzbot wrote:
> > > Hello,
> > > 
> > > syzbot found the following issue on:
> > > 
> > > HEAD commit:    d012a719 Linux 5.9-rc2
> > > git tree:       upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=15aa650e900000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=891ca5711a9f1650
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=c92c93d1f1aaaacdb9db
> > > compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> > > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12ecb939900000
> > > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=140a19a9900000
> > > 
> > > The issue was bisected to:
> > > 
> > > commit a9ed4a6560b8562b7e2e2bed9527e88001f7b682
> > > Author: Marc Zyngier <maz@kernel.org>
> > > Date:   Wed Aug 19 16:12:17 2020 +0000
> > > 
> > >     epoll: Keep a reference on files added to the check list
> > > 
> > > bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=16a50519900000
> > > final oops:     https://syzkaller.appspot.com/x/report.txt?x=15a50519900000
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=11a50519900000
> > > 
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+c92c93d1f1aaaacdb9db@syzkaller.appspotmail.com
> > > Fixes: a9ed4a6560b8 ("epoll: Keep a reference on files added to the check list")
> > > 
> > > ------------[ cut here ]------------
> > > kernel BUG at fs/inode.c:1668!
> > 
> > #syz set subsystem: fs
> > 
> > This has been among btrfs bugs but this is is 'fs' and probably with a
> > fix but I was not able to identify it among all the changes in
> > eventpoll.c
> 
> It has nothing to do with btrfs, and there's a good chance it had been
> fixed as a side effect of 319c15174757 "epoll: take epitem list out of struct file"
> merge at 1a825a6a0e7e in 5.10 merge window; IOW, it should be in 5.11-rc1.

Ok, thanks, let's use the commit 319c15174757 as the fix,

#syz fix: epoll: take epitem list out of struct file