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Subject: Re: [syzbot] WARNING in io_wqe_enqueue
To:     syzbot <syzbot+ea2f1484cffe5109dc10@syzkaller.appspotmail.com>,
        asml.silence@gmail.com, axboe@kernel.dk, io-uring@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk
References: <0000000000000bdfa905c3f6720f@google.com>
From:   Hao Xu <haoxu@linux.alibaba.com>
Message-ID: <b9cb6dc4-3dfe-de60-a933-1f423301b3ca@linux.alibaba.com>
Date:   Tue, 8 Jun 2021 17:47:24 +0800
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在 2021/6/5 上午4:22, syzbot 写道:
> syzbot has bisected this issue to:
> 
> commit 24369c2e3bb06d8c4e71fd6ceaf4f8a01ae79b7c
> Author: Pavel Begunkov <asml.silence@gmail.com>
> Date:   Tue Jan 28 00:15:48 2020 +0000
> 
>      io_uring: add io-wq workqueue sharing
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17934777d00000
> start commit:   f88cd3fb Merge tag 'vfio-v5.13-rc5' of git://github.com/aw..
> git tree:       upstream
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=14534777d00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=10534777d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=82d85e75046e5e64
> dashboard link: https://syzkaller.appspot.com/bug?extid=ea2f1484cffe5109dc10
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16d5772fd00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10525947d00000
> 
> Reported-by: syzbot+ea2f1484cffe5109dc10@syzkaller.appspotmail.com
> Fixes: 24369c2e3bb0 ("io_uring: add io-wq workqueue sharing")
> 
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
This is not a bug, the repro program first set RLIMIT_NPROC to 0, then 
submits an unbound work whcih raises a warning of
WARN_ON_ONCE(!acct->max_workers). Since unbound->max_workers is
task_rlimit(current, RLIMIT_NPROC), so it is expected.