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[209.85.220.65]) by mx.google.com with SMTPS id b199sor15095502itb.8.2019.03.18.05.18.15 for (Google Transport Security); Mon, 18 Mar 2019 05:18:15 -0700 (PDT) Received-SPF: pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=bCteQWEQ; spf=pass (google.com: domain of dvyukov@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=dvyukov@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vhc34cp7ul6RIl6hg+LkbLQXlFAa0bux2b/Uv9Q+8ds=; b=bCteQWEQ7a/Ce7oIkJ1ujPxTtZS+qerrJQHyfzureR3wkS/5C/gAbvuFtJG6ThrhyO C4pX5UA8d9+RGyn6WTHzp6nd2w2c2L7buxUxRipO7Mgn3QFOGn2Y1AI//Lbjti2FQVZy 0BOyJGm0q5zj2uE9R8LNQQLrMMIuUmJyQkL5wO3Aard9e0FjHdoefmYrNVyyKyEmAv6w Hu42TJXs3DEaZ2eJLoZ9KscGeLNW0I+B3ORdCTxRt9G0o4h/B6U5iCJCz10rHua2W9Fj KeyKyl7foWVC2Af5T6jTrbhatV2VqrnwnLN/KOGhTlPW6oVV7tJ7g3cpdkwyCkaGC05r 4bYw== X-Google-Smtp-Source: APXvYqwQ0AI6IjXA3aCfxfTc3KyOKQxDZ+P2Awfq0baql/7lUUDE4keKZuNVwYzFTm/Uh0NB+GgZM24tiSMcTrYjWx0= X-Received: by 2002:a05:660c:3d1:: with SMTP id c17mr9678695itl.166.1552911495269; Mon, 18 Mar 2019 05:18:15 -0700 (PDT) MIME-Version: 1.0 References: <0000000000007da94e05827ea99a@google.com> <0000000000009b8d8a058447efc5@google.com> <20190317110447.GA3885@kroah.com> In-Reply-To: <20190317110447.GA3885@kroah.com> From: Dmitry Vyukov Date: Mon, 18 Mar 2019 13:18:04 +0100 Message-ID: Subject: Re: WARNING in rcu_check_gp_start_stall To: Greg KH Cc: syzbot , Borislav Petkov , "open list:ANDROID DRIVERS" , Dou Liyang , forest@alittletooquiet.net, "H. Peter Anvin" , konrad.wilk@oracle.com, Len Brown , LKML , Linux-MM , Ingo Molnar , Peter Zijlstra , puwen@hygon.cn, syzkaller-bugs , Thomas Gleixner , tvboxspy@gmail.com, wang.yi59@zte.com.cn, "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Mar 17, 2019 at 12:04 PM Greg KH wrote: > > On Sun, Mar 17, 2019 at 03:43:01AM -0700, syzbot wrote: > > syzbot has bisected this bug to: > > > > commit f1e3e92135202ff3d95195393ee62808c109208c > > Author: Malcolm Priestley > > Date: Wed Jul 22 18:16:42 2015 +0000 > > > > staging: vt6655: fix tagSRxDesc -> next_desc type > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=111856cf200000 > > start commit: f1e3e921 staging: vt6655: fix tagSRxDesc -> next_desc type > > git tree: upstream > > final crash: https://syzkaller.appspot.com/x/report.txt?x=131856cf200000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=151856cf200000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=7132344728e7ec3f > > dashboard link: https://syzkaller.appspot.com/bug?extid=111bc509cd9740d7e4aa > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d4966cc00000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10c492d0c00000 > > > > Reported-by: syzbot+111bc509cd9740d7e4aa@syzkaller.appspotmail.com > > Fixes: f1e3e921 ("staging: vt6655: fix tagSRxDesc -> next_desc type") > > I think syzbot is a bit confused here, how can this simple patch, where > you do not have the hardware for this driver, cause this problem? Yes, I guess so. This perf_event_open+sched_setattr combo bug causes problems with hangs at random places, developers looking at these hangs again and again, incorrect bisection. I would be useful if somebody knowledgeable in perf/sched look at it.