linux-kernel - Re: [syzbot] riscv/fixes boot error: INFO: rcu detected stall in corrupted

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Message-ID: <CACT4Y+Yv7nuPkoQtAqu05K30hiq45ZYjPy-q5PAUHjJutydKig@mail.gmail.com>
Date:   Wed, 15 Feb 2023 09:46:28 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     syzbot <syzbot+42670398d6ddb118138f@...kaller.appspotmail.com>
Cc:     aou@...s.berkeley.edu, brauner@...nel.org, bristot@...hat.com,
        bsegall@...gle.com, dietmar.eggemann@....com,
        juri.lelli@...hat.com, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, mgorman@...e.de, mingo@...hat.com,
        palmer@...belt.com, paul.walmsley@...ive.com, peterz@...radead.org,
        rostedt@...dmis.org, syzkaller-bugs@...glegroups.com,
        vincent.guittot@...aro.org, vschneid@...hat.com,
        Alex Ghiti <alex@...ti.fr>
Subject: Re: [syzbot] riscv/fixes boot error: INFO: rcu detected stall in corrupted

On Wed, 15 Feb 2023 at 01:24, syzbot
<syzbot+42670398d6ddb118138f@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    950b879b7f02 riscv: Fixup race condition on PG_dcache_clea..
> git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
> console output: https://syzkaller.appspot.com/x/log.txt?x=137aaec0c80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=b3cd714c8e9a6e01
> dashboard link: https://syzkaller.appspot.com/bug?extid=42670398d6ddb118138f
> compiler:       riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: riscv64
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+42670398d6ddb118138f@...kaller.appspotmail.com
>
> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
> rcu:    0-...0: (1 GPs behind) idle=36ec/1/0x4000000000000000 softirq=6589/6590 fqs=9960
>         (detected by 1, t=30504 jiffies, g=14713, q=4 ncpus=2)
> Task dump for CPU 0:
> task:cmp             state:R  running task     stack:0     pid:2746  ppid:2744   flags:0x00000008
> Call Trace:
> [<ffffffff834348b8>] context_switch kernel/sched/core.c:5244 [inline]
> [<ffffffff834348b8>] __schedule+0x624/0x1254 kernel/sched/core.c:6555
> rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
> rcu:    0-...0: (1 GPs behind) idle=36ec/1/0x4000000000000000 softirq=6589/6590 fqs=28261
>         (detected by 1, t=122009 jiffies, g=14713, q=4 ncpus=2)
> Task dump for CPU 0:
> task:cmp             state:R  running task     stack:0     pid:2746  ppid:2744   flags:0x00000008
> Call Trace:
> [<ffffffff834348b8>] context_switch kernel/sched/core.c:5244 [inline]
> [<ffffffff834348b8>] __schedule+0x624/0x1254 kernel/sched/core.c:6555

Humm... initially I thought this may be related to the riscv issue
with too short command line (commit "riscv: Bump COMMAND_LINE_SIZE
value to 1024").

But it seems this actually fired after 300 seconds, right? (300
seconds is the intended timeout on syzbot):

>         (detected by 1, t=30504 jiffies, g=14713, q=4 ncpus=2)