Hello, syzbot found the following issue on: HEAD commit: 7c8ca812 Add linux-next specific files for 20201117 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=12d2d191500000 kernel config: https://syzkaller.appspot.com/x/.config?x=ff4bc71371dc5b13 dashboard link: https://syzkaller.appspot.com/bug?extid=c0d52d0b3c0c3ffb9525 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1481166a500000 The issue was bisected to: commit 4d004099a668c41522242aa146a38cc4eb59cb1e Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Fri Oct 2 09:04:21 2020 +0000 lockdep: Fix lockdep recursion bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10401726500000 final oops: https://syzkaller.appspot.com/x/report.txt?x=12401726500000 console output: https://syzkaller.appspot.com/x/log.txt?x=14401726500000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c0d52d0b3c0c3ffb9525@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 4d004099a668 ("lockdep: Fix lockdep recursion") INFO: task syz-executor.0:9557 blocked for more than 143 seconds. Not tainted 5.10.0-rc4-next-20201117-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor.0 state:D stack:28584 pid: 9557 ppid: 8485 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:4269 [inline] __schedule+0x890/0x2030 kernel/sched/core.c:5019 schedule+0xcf/0x270 kernel/sched/core.c:5098 io_uring_cancel_files fs/io_uring.c:8720 [inline] io_uring_cancel_task_requests fs/io_uring.c:8772 [inline] __io_uring_files_cancel+0xc4d/0x14b0 fs/io_uring.c:8868 io_uring_files_cancel include/linux/io_uring.h:51 [inline] exit_files+0xe4/0x170 fs/file.c:456 do_exit+0xb61/0x29f0 kernel/exit.c:818 do_group_exit+0x125/0x310 kernel/exit.c:920 get_signal+0x3ea/0x1f70 kernel/signal.c:2750 arch_do_signal_or_restart+0x2a6/0x1ea0 arch/x86/kernel/signal.c:811 handle_signal_work kernel/entry/common.c:145 [inline] exit_to_user_mode_loop kernel/entry/common.c:169 [inline] exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:199 syscall_exit_to_user_mode+0x38/0x260 kernel/entry/common.c:274 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45deb9 Code: Unable to access opcode bytes at RIP 0x45de8f. RSP: 002b:00007fa68397ccf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000118bf28 RCX: 000000000045deb9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000118bf28 RBP: 000000000118bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c R13: 00007fff50acc9af R14: 00007fa68397d9c0 R15: 000000000118bf2c Showing all locks held in the system: 1 lock held by khungtaskd/1654: #0: ffffffff8b339ca0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6252 1 lock held by in:imklog/8177: #0: ffff88801cf22d70 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:932 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1654 Comm: khungtaskd Not tainted 5.10.0-rc4-next-20201117-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x107/0x163 lib/dump_stack.c:120 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline] watchdog+0xd89/0xf30 kernel/hung_task.c:338 kthread+0x3af/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4887 Comm: systemd-journal Not tainted 5.10.0-rc4-next-20201117-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x4/0x20 kernel/kcov.c:284 Code: 84 00 00 00 00 00 48 8b 0c 24 0f b7 d6 0f b7 f7 bf 03 00 00 00 e9 cc fe ff ff 66 90 66 2e 0f 1f 84 00 00 00 00 00 48 8b 0c 24 <89> f2 89 fe bf 05 00 00 00 e9 ae fe ff ff 0f 1f 40 00 66 2e 0f 1f RSP: 0018:ffffc90000f0fe90 EFLAGS: 00000206 RAX: 0000000000000000 RBX: 0000000000080042 RCX: ffffffff81bd2a21 RDX: ffff88802594b500 RSI: 0000000000000040 RDI: 0000000000000000 RBP: 1ffff920001e1fd3 R08: 0000000000000000 R09: ffff8880110f3c17 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000040 R13: 00000000000001a0 R14: 00005616bdf3c270 R15: 0000000000000000 FS: 00007f934ff098c0(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000a47b58 CR3: 0000000026162000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: build_open_how fs/open.c:989 [inline] do_sys_open fs/open.c:1183 [inline] __do_sys_open fs/open.c:1192 [inline] __se_sys_open fs/open.c:1188 [inline] __x64_sys_open+0x171/0x1c0 fs/open.c:1188 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f934f499840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007ffc6cf30568 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007ffc6cf30870 RCX: 00007f934f499840 RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 00005616bdf3c270 RBP: 000000000000000d R08: 0000000000000000 R09: 00000000ffffffff R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff R13: 00005616bdf30040 R14: 00007ffc6cf30830 R15: 00005616bdf3cef0 --- This report 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@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
