INFO: task syz-executor100:7987 blocked for more than 140 seconds. Not tainted 4.14.272-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor100 D28376 7987 7985 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 fuse_wait_on_page_writeback fs/fuse/file.c:385 [inline] fuse_wait_on_page_writeback.isra.0+0xdc/0x120 fs/fuse/file.c:381 fuse_launder_page fs/fuse/file.c:2041 [inline] fuse_launder_page+0xa2/0xd0 fs/fuse/file.c:2034 do_launder_page mm/truncate.c:609 [inline] invalidate_inode_pages2_range+0x547/0xc00 mm/truncate.c:685 fuse_finish_open+0x262/0x500 fs/fuse/file.c:181 fuse_open_common+0x234/0x290 fs/fuse/file.c:224 do_dentry_open+0x44b/0xec0 fs/open.c:777 vfs_open+0x105/0x220 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0x628/0x2970 fs/namei.c:3569 do_filp_open+0x179/0x3c0 fs/namei.c:3603 do_sys_open+0x296/0x410 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7fd5c2be74b9 RSP: 002b:00007fd5c2b982f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055 RAX: ffffffffffffffda RBX: 00007fd5c2c784c0 RCX: 00007fd5c2be74b9 RDX: 00007fd5c2be74b9 RSI: 0000000000000000 RDI: 00000000200001c0 RBP: 00007fd5c2c45154 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e R13: 00007fd5c2c41148 R14: 00007fd5c2c43150 R15: 00007fd5c2c784c8 Showing all locks held in the system: 1 lock held by khungtaskd/1533: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 2 locks held by syz-executor100/7987: #0: (sb_writers#10){.+.+}, at: [] sb_start_write include/linux/fs.h:1551 [inline] #0: (sb_writers#10){.+.+}, at: [] mnt_want_write+0x3a/0xb0 fs/namespace.c:386 #1: (&sb->s_type->i_mutex_key#17){+.+.}, at: [] inode_lock include/linux/fs.h:719 [inline] #1: (&sb->s_type->i_mutex_key#17){+.+.}, at: [] fuse_open_common+0x1a4/0x290 fs/fuse/file.c:217 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1533 Comm: khungtaskd Not tainted 4.14.272-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: 8 Comm: rcu_preempt Not tainted 4.14.272-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880b5420200 task.stack: ffff8880b5428000 RIP: 0010:trace_lock_acquire include/trace/events/lock.h:13 [inline] RIP: 0010:lock_acquire+0x139/0x3f0 kernel/locking/lockdep.c:3997 RSP: 0018:ffff8880b542fb50 EFLAGS: 00000097 RAX: 0000000000000001 RBX: ffff8880b5420200 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8880b5420a84 RBP: ffff8880ba52cb18 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f07cb503000 CR3: 00000000a19fc000 CR4: 00000000003406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x8c/0xc0 kernel/locking/spinlock.c:160 lock_timer_base+0x58/0x190 kernel/time/timer.c:922 try_to_del_timer_sync+0x6a/0xe0 kernel/time/timer.c:1178 del_timer_sync+0x17c/0x240 kernel/time/timer.c:1246 schedule_timeout+0x4b7/0xe90 kernel/time/timer.c:1748 rcu_gp_kthread+0xc0a/0x1e60 kernel/rcu/tree.c:2255 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: 00 00 c7 83 84 08 00 00 01 00 00 00 0f 1f 44 00 00 65 8b 05 5a 4a c0 7e 83 f8 07 0f 87 02 02 00 00 89 c0 48 0f a3 05 2f 79 c7 08 <0f> 82 b5 01 00 00 4c 8b 4c 24 08 44 89 ea 6a 00 48 89 ef 6a 00 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: c7 83 84 08 00 00 01 movl $0x1,0x884(%rbx) 9: 00 00 00 c: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 11: 65 8b 05 5a 4a c0 7e mov %gs:0x7ec04a5a(%rip),%eax # 0x7ec04a72 18: 83 f8 07 cmp $0x7,%eax 1b: 0f 87 02 02 00 00 ja 0x223 21: 89 c0 mov %eax,%eax 23: 48 0f a3 05 2f 79 c7 bt %rax,0x8c7792f(%rip) # 0x8c7795a 2a: 08 * 2b: 0f 82 b5 01 00 00 jb 0x1e6 <-- trapping instruction 31: 4c 8b 4c 24 08 mov 0x8(%rsp),%r9 36: 44 89 ea mov %r13d,%edx 39: 6a 00 pushq $0x0 3b: 48 89 ef mov %rbp,%rdi 3e: 6a 00 pushq $0x0