INFO: task syz-executor0:17624 blocked for more than 140 seconds. Not tainted 4.19.0-rc5+ #29 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor0 D18920 17624 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x86c/0x1ed0 kernel/sched/core.c:3473 schedule+0xfe/0x460 kernel/sched/core.c:3517 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 fuse_lock_inode+0xba/0xf0 fs/fuse/inode.c:365 fuse_lookup+0x8f/0x4c0 fs/fuse/dir.c:360 __lookup_slow+0x2b5/0x540 fs/namei.c:1671 lookup_slow+0x57/0x80 fs/namei.c:1688 walk_component+0x92b/0x25c0 fs/namei.c:1810 link_path_walk.part.40+0xa61/0x1530 fs/namei.c:2141 link_path_walk fs/namei.c:2072 [inline] path_mountpoint+0x103/0x2190 fs/namei.c:2694 filename_mountpoint+0x245/0x460 fs/namei.c:2717 user_path_mountpoint_at+0x37/0x40 fs/namei.c:2747 ksys_umount+0x1c9/0x12a0 fs/namespace.c:1639 __do_sys_umount fs/namespace.c:1665 [inline] __se_sys_umount fs/namespace.c:1663 [inline] __x64_sys_umount+0x54/0x80 fs/namespace.c:1663 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459fc7 Code: Bad RIP value. RSP: 002b:00007fff5d8d9538 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6 RAX: ffffffffffffffda RBX: 000000000011ef09 RCX: 0000000000459fc7 RDX: 0000000000402e70 RSI: 0000000000000002 RDI: 00007fff5d8d95e0 RBP: 0000000000000c57 R08: 0000000000000000 R09: 0000000000000011 R10: 000000000000000a R11: 0000000000000206 R12: 00007fff5d8da670 R13: 0000000000d19940 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/979: #0: 000000008f68733f (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 1 lock held by rsyslogd/5239: #0: 000000003fba62a5 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5329: #0: 0000000071238b19 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b4b84e0d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5330: #0: 00000000ac2cc49f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000033da95c5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5331: #0: 00000000046ae880 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d9bd037e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5332: #0: 0000000083d6be04 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000001ac2c8c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5333: #0: 0000000015bead1b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b6835b5b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5334: #0: 00000000e9cbd568 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000006b5a2ddd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5335: #0: 0000000031558e8c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000ce0ea76e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor0/17624: #0: 0000000004e2a391 (&type->i_mutex_dir_key#9){++++}, at: inode_lock_shared include/linux/fs.h:748 [inline] #0: 0000000004e2a391 (&type->i_mutex_dir_key#9){++++}, at: lookup_slow+0x49/0x80 fs/namei.c:1687 #1: 00000000b12a2c9b (&fi->mutex){+.+.}, at: fuse_lock_inode+0xba/0xf0 fs/fuse/inode.c:365 2 locks held by syz-executor1/3055: #0: 0000000031ddef3f (sb_writers#19){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 0000000031ddef3f (sb_writers#19){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 0000000026907138 (&type->i_mutex_dir_key#9){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 0000000026907138 (&type->i_mutex_dir_key#9){++++}, at: chmod_common+0x1b1/0x590 fs/open.c:535 2 locks held by syz-executor0/6047: #0: 00000000e757c409 (sb_writers#19){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 00000000e757c409 (sb_writers#19){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 00000000b10913e2 (&type->i_mutex_dir_key#9){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 00000000b10913e2 (&type->i_mutex_dir_key#9){++++}, at: chmod_common+0x1b1/0x590 fs/open.c:535 2 locks held by syz-executor0/6111: #0: 000000004134f3d3 (sb_writers#19){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 000000004134f3d3 (sb_writers#19){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 00000000913ff96d (&type->i_mutex_dir_key#9){++++}, at: inode_lock include/linux/fs.h:738 [inline] #1: 00000000913ff96d (&type->i_mutex_dir_key#9){++++}, at: chmod_common+0x1b1/0x590 fs/open.c:535 2 locks held by syz-executor0/6783: #0: 0000000004e2a391 (&type->i_mutex_dir_key#9){++++}, at: inode_lock_shared include/linux/fs.h:748 [inline] #0: 0000000004e2a391 (&type->i_mutex_dir_key#9){++++}, at: lookup_slow+0x49/0x80 fs/namei.c:1687 #1: 00000000b12a2c9b (&fi->mutex){+.+.}, at: fuse_lock_inode+0xba/0xf0 fs/fuse/inode.c:365 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 979 Comm: khungtaskd Not tainted 4.19.0-rc5+ #29 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b3/0x1ed lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb3e/0x1050 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3195 Comm: udevd Not tainted 4.19.0-rc5+ #29 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:write_comp_data+0x0/0x70 Code: e8 25 62 43 00 e9 a6 fc ff ff 4c 89 f7 e8 78 61 43 00 e9 6f fc ff ff e8 3e eb c9 ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <55> 65 4c 8b 04 25 40 ee 01 00 65 8b 05 0f 0a 83 7e a9 00 01 1f 00 RSP: 0018:ffff8801c750f8a0 EFLAGS: 00000246 RAX: ffff8801c7502180 RBX: 1ffff10038ea1f19 RCX: ffffffff81d439d6 RDX: 00000000002dc6bf RSI: 000000000000c350 RDI: 0000000000000006 RBP: ffff8801c750f8a8 R08: ffff8801c7502180 R09: 000000000000000c R10: ffffed00390ce480 R11: 0000000000000001 R12: 000000000000c350 R13: 000000003b9ac739 R14: 0000000000000064 R15: 00000000002dc6bf FS: 00007fe6f73187a0(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001c7b30000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: select_estimate_accuracy+0x336/0x4b0 fs/select.c:90 ep_poll+0x6d9/0x13d0 fs/eventpoll.c:1758 do_epoll_wait+0x1b0/0x200 fs/eventpoll.c:2198 __do_sys_epoll_wait fs/eventpoll.c:2208 [inline] __se_sys_epoll_wait fs/eventpoll.c:2205 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2205 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fe6f6a2c943 Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24 RSP: 002b:00007ffcd068a698 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007fe6f6a2c943 RDX: 0000000000000008 RSI: 00007ffcd068a790 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 0000000001c826b0 R15: 0000000001c61250