From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kirill Tkhai Subject: Re: WARNING in kcm_exit_net (3) Date: Thu, 31 May 2018 12:58:56 +0300 Message-ID: <4b0d0053-60f4-ac5e-f228-4c19c46d85ef@virtuozzo.com> References: <00000000000000dca5056d7c1442@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit To: syzbot , davem@davemloft.net, ebiggers@google.com, edumazet@google.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, tom@quantonium.net, viro@ZenIV.linux.org.uk Return-path: In-Reply-To: <00000000000000dca5056d7c1442@google.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 31.05.2018 11:16, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit:    d60d61f36b8f Merge branch 'for-linus' of git://git.kernel... > git tree:       upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=101bb52f800000 > kernel config:  https://syzkaller.appspot.com/x/.config?x=968b0b23c7854c0b > dashboard link: https://syzkaller.appspot.com/bug?extid=5f1a04e374a635efc426 > compiler:       gcc (GCC) 8.0.1 20180413 (experimental) > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13b9ed2f800000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+5f1a04e374a635efc426@syzkaller.appspotmail.com > > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > IPVS: ftp: loaded support on port[0] = 21 > WARNING: CPU: 0 PID: 6 at net/kcm/kcmsock.c:2023 kcm_exit_net+0x392/0x3e0 net/kcm/kcmsock.c:2023 Hm, there is allocated a kernel socket in kcm_clone(). It does not get net counter and it seems kcm_done_work() may complete after kcm_exit_net() is completed. So, it looks like we have to flush work queue in kcm_exit_net(). > Kernel panic - not syncing: panic_on_warn set ... > > CPU: 0 PID: 6 Comm: kworker/u4:0 Not tainted 4.17.0-rc7+ #75 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: netns cleanup_net > Call Trace: >  __dump_stack lib/dump_stack.c:77 [inline] >  dump_stack+0x1b9/0x294 lib/dump_stack.c:113 >  panic+0x22f/0x4de kernel/panic.c:184 >  __warn.cold.8+0x163/0x1b3 kernel/panic.c:536 >  report_bug+0x252/0x2d0 lib/bug.c:186 >  fixup_bug arch/x86/kernel/traps.c:178 [inline] >  do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296 >  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315 >  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992 > RIP: 0010:kcm_exit_net+0x392/0x3e0 net/kcm/kcmsock.c:2023 > RSP: 0018:ffff8801d9a97430 EFLAGS: 00010293 > RAX: ffff8801d9a88180 RBX: 1ffff1003b352e86 RCX: 1ffff1003b351135 > RDX: 0000000000000000 RSI: ffffffff86d56942 RDI: 0000000000000286 > RBP: ffff8801d9a974f8 R08: 1ffff1003b352e67 R09: ffffed003b5c46d2 > R10: 0000000000000003 R11: 0000000000000003 R12: 1ffff1003b352e8a > R13: ffff8801d9a974d0 R14: ffff8801d96763d0 R15: ffff8801c51d0e00 >  ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152 >  cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523 >  process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145 >  worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279 >  kthread+0x345/0x410 kernel/kthread.c:240 >  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 > Dumping ftrace buffer: >    (ftrace buffer empty) > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot. > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches