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Mon, 31 Aug 2020 13:58:14 -0700 (PDT) Date: Mon, 31 Aug 2020 13:58:14 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <00000000000040b7ba05ae32a94a@google.com> Subject: possible deadlock in __sock_release From: syzbot To: davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: b36c9697 Add linux-next specific files for 20200828 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=10bf2835900000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e3cf99580b5542c dashboard link: https://syzkaller.appspot.com/bug?extid=8e467b009209f1fcf666 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12be1435900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f77ad1900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8e467b009209f1fcf666@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 5.9.0-rc2-next-20200828-syzkaller #0 Not tainted ------------------------------------------------------ kworker/0:4/7108 is trying to acquire lock: ffff888085730c90 (&sb->s_type->i_mutex_key#13){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:779 [inline] ffff888085730c90 (&sb->s_type->i_mutex_key#13){+.+.}-{3:3}, at: __sock_release+0x86/0x280 net/socket.c:595 but task is already holding lock: ffffc90006037da8 ((delayed_fput_work).work){+.+.}-{0:0}, at: process_one_work+0x85f/0x1670 kernel/workqueue.c:2244 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 ((delayed_fput_work).work){+.+.}-{0:0}: process_one_work+0x8bb/0x1670 kernel/workqueue.c:2245 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #2 ((wq_completion)events){+.+.}-{0:0}: flush_workqueue+0x110/0x13e0 kernel/workqueue.c:2780 flush_scheduled_work include/linux/workqueue.h:597 [inline] tipc_exit_net+0x47/0x2a0 net/tipc/core.c:116 ops_exit_list+0xb0/0x160 net/core/net_namespace.c:186 cleanup_net+0x4ea/0xb10 net/core/net_namespace.c:603 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 -> #1 (pernet_ops_rwsem){++++}-{3:3}: down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 unregister_netdevice_notifier+0x1e/0x170 net/core/dev.c:1861 raw_release+0x58/0x890 net/can/raw.c:354 __sock_release+0xcd/0x280 net/socket.c:596 sock_close+0x18/0x20 net/socket.c:1277 __fput+0x285/0x920 fs/file_table.c:281 task_work_run+0xdd/0x190 kernel/task_work.c:141 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_user_mode_loop kernel/entry/common.c:140 [inline] exit_to_user_mode_prepare+0x195/0x1c0 kernel/entry/common.c:167 syscall_exit_to_user_mode+0x59/0x2b0 kernel/entry/common.c:242 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&sb->s_type->i_mutex_key#13){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2a6b/0x5640 kernel/locking/lockdep.c:4426 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:779 [inline] __sock_release+0x86/0x280 net/socket.c:595 sock_close+0x18/0x20 net/socket.c:1277 __fput+0x285/0x920 fs/file_table.c:281 delayed_fput+0x56/0x70 fs/file_table.c:309 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#13 --> (wq_completion)events --> (delayed_fput_work).work Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((delayed_fput_work).work); lock((wq_completion)events); lock((delayed_fput_work).work); lock(&sb->s_type->i_mutex_key#13); *** DEADLOCK *** 2 locks held by kworker/0:4/7108: #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff8880aa063d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x82b/0x1670 kernel/workqueue.c:2240 #1: ffffc90006037da8 ((delayed_fput_work).work){+.+.}-{0:0}, at: process_one_work+0x85f/0x1670 kernel/workqueue.c:2244 stack backtrace: CPU: 0 PID: 7108 Comm: kworker/0:4 Not tainted 5.9.0-rc2-next-20200828-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events delayed_fput Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 check_noncircular+0x324/0x3e0 kernel/locking/lockdep.c:1827 check_prev_add kernel/locking/lockdep.c:2496 [inline] check_prevs_add kernel/locking/lockdep.c:2601 [inline] validate_chain kernel/locking/lockdep.c:3218 [inline] __lock_acquire+0x2a6b/0x5640 kernel/locking/lockdep.c:4426 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:5005 down_write+0x8d/0x150 kernel/locking/rwsem.c:1531 inode_lock include/linux/fs.h:779 [inline] __sock_release+0x86/0x280 net/socket.c:595 sock_close+0x18/0x20 net/socket.c:1277 __fput+0x285/0x920 fs/file_table.c:281 delayed_fput+0x56/0x70 fs/file_table.c:309 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415 kthread+0x3b5/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 --- This report is generated by a bot. 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