INFO: task syz-executor.1:16940 blocked for more than 140 seconds. Not tainted 4.14.262-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D29112 16940 7995 0x00000004 Call Trace: context_switch kernel/sched/core.c:2811 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 schedule_timeout+0x80a/0xe90 kernel/time/timer.c:1724 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x272/0x430 kernel/sched/completion.c:123 flush_work+0x3fe/0x770 kernel/workqueue.c:2894 __cancel_work_timer+0x321/0x460 kernel/workqueue.c:2965 p9_conn_destroy net/9p/trans_fd.c:899 [inline] p9_fd_close+0x299/0x420 net/9p/trans_fd.c:925 p9_client_create+0x736/0x12c0 net/9p/client.c:1095 v9fs_session_init+0x1c5/0x1540 fs/9p/v9fs.c:422 v9fs_mount+0x73/0x860 fs/9p/vfs_super.c:135 mount_fs+0x92/0x2a0 fs/super.c:1237 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046 vfs_kern_mount fs/namespace.c:1036 [inline] do_new_mount fs/namespace.c:2572 [inline] do_mount+0xe65/0x2a10 fs/namespace.c:2902 SYSC_mount fs/namespace.c:3118 [inline] SyS_mount+0xa8/0x120 fs/namespace.c:3095 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f5dd6709fe9 RSP: 002b:00007f5dd501c168 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f5dd681d1d0 RCX: 00007f5dd6709fe9 RDX: 00000000200001c0 RSI: 0000000020000240 RDI: 0000000000000000 RBP: 00007f5dd676408d R08: 0000000020000340 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc641072af R14: 00007f5dd501c300 R15: 0000000000022000 Showing all locks held in the system: 2 locks held by kworker/0:1/24: #0: ("events"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088 #1: ((&m->wq)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092 1 lock held by khungtaskd/1534: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1534 Comm: khungtaskd Not tainted 4.14.262-syzkaller #0 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+0x1b2/0x281 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 7683 Comm: rs:main Q:Reg Not tainted 4.14.262-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff88808fcc0240 task.stack: ffff88808fcb0000 RIP: 0010:__sanitizer_cov_trace_pc+0x9/0x50 kernel/kcov.c:65 RSP: 0018:ffff88808fcb77e8 EFLAGS: 00000293 RAX: ffff88808fcc0240 RBX: dffffc0000000000 RCX: 0000000000000000 RDX: 1ffff11012ea7c95 RSI: ffffffff879381a0 RDI: ffff88809753e4a8 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000003 R10: 0000000000000000 R11: ffff88808fcc0240 R12: 0000000000001000 R13: 0000000000000000 R14: ffff88809753e498 R15: ffffea00012e42c0 FS: 00007fbf33598700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f135af4e000 CR3: 00000000b3415000 CR4: 00000000003406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: set_bh_page fs/buffer.c:1483 [inline] alloc_page_buffers+0x77/0x1f0 fs/buffer.c:885 create_empty_buffers+0x36/0x450 fs/buffer.c:1590 create_page_buffers+0x14d/0x1c0 fs/buffer.c:1707 __block_write_begin_int+0x176/0x1090 fs/buffer.c:2017 ext4_da_write_begin+0x402/0xe70 fs/ext4/inode.c:3116 generic_perform_write+0x1c9/0x420 mm/filemap.c:3055 __generic_file_write_iter+0x227/0x590 mm/filemap.c:3180 ext4_file_write_iter+0x276/0xd20 fs/ext4/file.c:270 call_write_iter include/linux/fs.h:1780 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x44c/0x630 fs/read_write.c:482 vfs_write+0x17f/0x4d0 fs/read_write.c:544 SYSC_write fs/read_write.c:590 [inline] SyS_write+0xf2/0x210 fs/read_write.c:582 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fbf35fdc1cd RSP: 002b:00007fbf33597590 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fbf28024f40 RCX: 00007fbf35fdc1cd RDX: 00000000000004a6 RSI: 00007fbf28024f40 RDI: 0000000000000008 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00007fbf28024cc0 R13: 00007fbf335975b0 R14: 00005649effc3440 R15: 00000000000004a6 Code: 00 e9 9f fe ff ff 4c 89 e7 e8 44 af 29 00 e9 2c fe ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 65 48 8b 04 25 c0 7f 02 00 <48> 85 c0 74 1a 65 8b 15 0b 44 ad 7e 81 e2 00 01 1f 00 75 0b 8b ---------------- Code disassembly (best guess), 1 bytes skipped: 0: e9 9f fe ff ff jmpq 0xfffffea4 5: 4c 89 e7 mov %r12,%rdi 8: e8 44 af 29 00 callq 0x29af51 d: e9 2c fe ff ff jmpq 0xfffffe3e 12: 90 nop 13: 90 nop 14: 90 nop 15: 90 nop 16: 90 nop 17: 90 nop 18: 90 nop 19: 90 nop 1a: 90 nop 1b: 90 nop 1c: 90 nop 1d: 90 nop 1e: 90 nop 1f: 90 nop 20: 90 nop 21: 65 48 8b 04 25 c0 7f mov %gs:0x27fc0,%rax 28: 02 00 * 2a: 48 85 c0 test %rax,%rax <-- trapping instruction 2d: 74 1a je 0x49 2f: 65 8b 15 0b 44 ad 7e mov %gs:0x7ead440b(%rip),%edx # 0x7ead4441 36: 81 e2 00 01 1f 00 and $0x1f0100,%edx 3c: 75 0b jne 0x49 3e: 8b .byte 0x8b