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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Mon, 17 May 2021 17:43:22 +0200
Message-ID: <CACT4Y+Z8VjfOU=eR-ijhkXJJuZLM4NC+ui5ce0R=OH6WVWwB1w@mail.gmail.com>
Subject: Re: [syzbot] WARNING in __perf_install_in_context
To:     Peter Zijlstra <peterz@infradead.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv <linux-riscv@lists.infradead.org>
Cc:     syzbot <syzbot+0fb24f56fa707081e4f2@syzkaller.appspotmail.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>, bpf <bpf@vger.kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        John Fastabend <john.fastabend@gmail.com>,
        Jiri Olsa <jolsa@redhat.com>, Martin KaFai Lau <kafai@fb.com>,
        KP Singh <kpsingh@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Ingo Molnar <mingo@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Song Liu <songliubraving@fb.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Yonghong Song <yhs@fb.com>
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On Mon, May 17, 2021 at 2:46 PM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Mon, May 17, 2021 at 1:28 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Mon, May 17, 2021 at 03:56:22AM -0700, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    18a3c5f7 Merge tag 'for_linus' of git://git.kernel.org/pub..
> > > 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=1662c153d00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=b8ac1fe5995f69d7
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=0fb24f56fa707081e4f2
> > > userspace arch: riscv64
> > >
> > > Unfortunately, I don't have any reproducer for this issue yet.
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+0fb24f56fa707081e4f2@syzkaller.appspotmail.com
> > >
> > > ------------[ cut here ]------------
> > > WARNING: CPU: 1 PID: 8643 at kernel/events/core.c:2781 __perf_install_in_context+0x1c0/0x47c kernel/events/core.c:2781
> > > Modules linked in:
> > > CPU: 1 PID: 8643 Comm: syz-executor.0 Not tainted 5.12.0-rc8-syzkaller-00011-g18a3c5f7abfd #0
> > > Hardware name: riscv-virtio,qemu (DT)
> >
> > How serious should I take this thing? ARM64 and x86_64 don't show these
> > errors.
>
> +riscv mainters for this question
> Is perf on riscv considered stable?

Another perf/riscv64 warning just come in:
https://syzkaller.appspot.com/bug?extid=30189c98403be62bc05a