Messages in this thread | | | Date | Sun, 25 Mar 2018 17:01:03 -0700 | Subject | possible deadlock in handle_rx | From | syzbot <> |
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Hello,
syzbot hit the following crash on upstream commit cb6416592bc2a8b731dabcec0d63cda270764fc6 (Sun Mar 25 17:45:10 2018 +0000) Merge tag 'dmaengine-fix-4.16-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/slave-dma syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=7f073540b1384a614e09
So far this crash happened 4 times on upstream. C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6506789075943424 syzkaller reproducer: https://syzkaller.appspot.com/x/repro.syz?id=5716250550337536 Raw console output: https://syzkaller.appspot.com/x/log.txt?id=5142038655795200 Kernel config: https://syzkaller.appspot.com/x/.config?id=-5034017172441945317 compiler: gcc (GCC) 7.1.1 20170620
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+7f073540b1384a614e09@syzkaller.appspotmail.com It will help syzbot understand when the bug is fixed. See footer for details. If you forward the report, please keep this part and the footer.
============================================ WARNING: possible recursive locking detected 4.16.0-rc6+ #366 Not tainted -------------------------------------------- vhost-4248/4760 is trying to acquire lock: (&vq->mutex){+.+.}, at: [<000000003482bddc>] vhost_net_rx_peek_head_len drivers/vhost/net.c:633 [inline] (&vq->mutex){+.+.}, at: [<000000003482bddc>] handle_rx+0xeb1/0x19c0 drivers/vhost/net.c:784
but task is already holding lock: (&vq->mutex){+.+.}, at: [<000000004de72f44>] handle_rx+0x1f5/0x19c0 drivers/vhost/net.c:766
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&vq->mutex); lock(&vq->mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by vhost-4248/4760: #0: (&vq->mutex){+.+.}, at: [<000000004de72f44>] handle_rx+0x1f5/0x19c0 drivers/vhost/net.c:766
stack backtrace: CPU: 0 PID: 4760 Comm: vhost-4248 Not tainted 4.16.0-rc6+ #366 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 print_deadlock_bug kernel/locking/lockdep.c:1761 [inline] check_deadlock kernel/locking/lockdep.c:1805 [inline] validate_chain kernel/locking/lockdep.c:2401 [inline] __lock_acquire+0xe8f/0x3e00 kernel/locking/lockdep.c:3431 lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0x16f/0x1a80 kernel/locking/mutex.c:893 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908 vhost_net_rx_peek_head_len drivers/vhost/net.c:633 [inline] handle_rx+0xeb1/0x19c0 drivers/vhost/net.c:784 handle_rx_net+0x19/0x20 drivers/vhost/net.c:910 vhost_worker+0x268/0x470 drivers/vhost/vhost.c:361 kthread+0x33c/0x400 kernel/kthread.c:238 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
--- This bug is generated by a dumb bot. It may contain errors. See https://goo.gl/tpsmEJ for details. Direct all questions to syzkaller@googlegroups.com.
syzbot will keep track of this bug report. If you forgot to add the Reported-by tag, once the fix for this bug is merged into any tree, please reply to this email with: #syz fix: exact-commit-title If you want to test a patch for this bug, please reply with: #syz test: git://repo/address.git branch and provide the patch inline or as an attachment. To mark this as a duplicate of another syzbot report, please reply with: #syz dup: exact-subject-of-another-report If it's a one-off invalid bug report, please reply with: #syz invalid Note: if the crash happens again, it will cause creation of a new bug report. Note: all commands must start from beginning of the line in the email body.
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