From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id E48BE6B06F7 for ; Sat, 12 May 2018 22:06:26 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id c4-v6so7244531pfg.22 for ; Sat, 12 May 2018 19:06:26 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [202.181.97.72]) by mx.google.com with ESMTPS id c22-v6si5400234pgn.169.2018.05.12.19.06.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 12 May 2018 19:06:25 -0700 (PDT) Subject: Re: BUG: workqueue lockup (2) From: Tetsuo Handa References: <94eb2c03c9bc75aff2055f70734c@google.com> <001a113f711a528a3f0560b08e76@google.com> <20180512215222.GC817@sol.localdomain> In-Reply-To: <20180512215222.GC817@sol.localdomain> Message-Id: <201805131106.GFF73973.OOtMVQFSFOJFHL@I-love.SAKURA.ne.jp> Date: Sun, 13 May 2018 11:06:17 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: ebiggers3@gmail.com, bot+e38be687a2450270a3b593bacb6b5795a7a74edb@syzkaller.appspotmail.com, peter@hurleysoftware.com Cc: dvyukov@google.com, gregkh@linuxfoundation.org, kstewart@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, pombredanne@nexb.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de Eric Biggers wrote: > The bug that this reproducer reproduces was fixed a while ago by commit > 966031f340185e, so I'm marking this bug report fixed by it: > > #syz fix: n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD) Nope. Commit 966031f340185edd ("n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD)") is "Wed Dec 20 17:57:06 2017 -0800" but the last occurrence on linux.git (commit 008464a9360e31b1 ("Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid")) is only a few days ago ("Wed May 9 10:49:52 2018 -1000"). > > Note that the error message was not always "BUG: workqueue lockup"; it was also > sometimes like "watchdog: BUG: soft lockup - CPU#5 stuck for 22s!". > > syzbot still is hitting the "BUG: workqueue lockup" error sometimes, but it must > be for other reasons. None has a reproducer currently. The last occurrence on linux.git is considered as a duplicate of [upstream] INFO: rcu detected stall in n_tty_receive_char_special https://syzkaller.appspot.com/bug?id=3d7481a346958d9469bebbeb0537d5f056bdd6e8 which we already have a reproducer at https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/YCVPocx3AgAJ and debug output is available at https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/TxQ7WS5ZAwAJ . We are currently waiting for comments from Peter Hurley who added that code.