INFO: task syz-executor394:7979 blocked for more than 140 seconds. Not tainted 4.14.275-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor394 D28376 7979 7977 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: 0033:0x7f76badac4c9 RSP: 002b:00007f76bad5d2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00007f76bae3d4c0 RCX: 00007f76badac4c9 RDX: 0000000000000000 RSI: 0000000000000700 RDI: 0000000020000100 RBP: 00007f76bae0a164 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e R13: 00007f76bae06158 R14: 00007f76bae08160 R15: 00007f76bae3d4c8 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 1 lock held by in:imklog/7694: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x1fb/0x2b0 fs/file.c:819 2 locks held by syz-executor394/7979: #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 4.14.275-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 4.14.275-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880b5420200 task.stack: ffff8880b5428000 RIP: 0010:__read_once_size include/linux/compiler.h:185 [inline] RIP: 0010:lookup_chain_cache kernel/locking/lockdep.c:2361 [inline] RIP: 0010:lookup_chain_cache_add kernel/locking/lockdep.c:2381 [inline] RIP: 0010:validate_chain kernel/locking/lockdep.c:2435 [inline] RIP: 0010:__lock_acquire+0xaab/0x3f20 kernel/locking/lockdep.c:3491 RSP: 0018:ffff8880b542fa48 EFLAGS: 00000802 RAX: 1ffffffff167dea7 RBX: ffffffff8b3ef520 RCX: 00000000000016aa RDX: 1ffffffff1736002 RSI: 00000000bcc77e12 RDI: ffffffff8b3ef538 RBP: dffffc0000000000 R08: ffffffff8b9b0010 R09: 00000000000c00cd R10: ffff8880b5420a88 R11: ffff8880b5420200 R12: ffff8880b5420aa0 R13: 0000000000000001 R14: 8c8f84168311dce9 R15: ffffffff8bed0d40 FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb523dc1018 CR3: 00000000a1126000 CR4: 00000000003406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 del_timer_sync+0xaf/0x240 kernel/time/timer.c:1236 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 fc ff df eb 06 48 83 eb 08 74 3d 48 8d 7b 18 48 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 24 1f 00 00 4c 3b 73 18 0f 84 81 fd ff ff <48> 8d 7b 08 48 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 9c 1e 00 00 ---------------- Code disassembly (best guess), 4 bytes skipped: 0: eb 06 jmp 0x8 2: 48 83 eb 08 sub $0x8,%rbx 6: 74 3d je 0x45 8: 48 8d 7b 18 lea 0x18(%rbx),%rdi c: 48 89 f8 mov %rdi,%rax f: 48 c1 e8 03 shr $0x3,%rax 13: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) 17: 0f 85 24 1f 00 00 jne 0x1f41 1d: 4c 3b 73 18 cmp 0x18(%rbx),%r14 21: 0f 84 81 fd ff ff je 0xfffffda8 * 27: 48 8d 7b 08 lea 0x8(%rbx),%rdi <-- trapping instruction 2b: 48 89 f8 mov %rdi,%rax 2e: 48 c1 e8 03 shr $0x3,%rax 32: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) 36: 0f 85 9c 1e 00 00 jne 0x1ed8