INFO: task syz-executor2:4815 blocked for more than 140 seconds. Not tainted 4.18.0-rc4+ #139 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D24216 4815 4594 0x00000004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x87c/0x1ed0 kernel/sched/core.c:3501 schedule+0xfb/0x450 kernel/sched/core.c:3545 __rwsem_down_write_failed_common+0x95d/0x1630 kernel/locking/rwsem-xadd.c:566 rwsem_down_write_failed+0xe/0x10 kernel/locking/rwsem-xadd.c:595 call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:117 __down_write arch/x86/include/asm/rwsem.h:142 [inline] down_write+0xaa/0x130 kernel/locking/rwsem.c:72 inode_lock include/linux/fs.h:715 [inline] chown_common+0x3a9/0x730 fs/open.c:640 do_fchownat+0x16e/0x250 fs/open.c:673 __do_sys_chown fs/open.c:693 [inline] __se_sys_chown fs/open.c:691 [inline] __x64_sys_chown+0x7b/0xc0 fs/open.c:691 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455e29 Code: cc 64 48 8b 0c 25 f8 ff ff ff 48 3b 61 10 0f 86 ab 04 00 00 48 83 ec 58 48 89 6c 24 50 48 8d 6c 24 50 48 8b 44 24 60 c6 00 00 <48> 8b 4c 24 68 48 89 ca 48 89 50 08 48 8b 59 20 48 01 da 31 db 31 RSP: 002b:00007f34778bcc68 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007f34778bd6d4 RCX: 0000000000455e29 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000140 RBP: 000000000072bff0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004c02d6 R14: 00000000004c8ea0 R15: 0000000000000002 Showing all locks held in the system: 1 lock held by khungtaskd/902: #0: 00000000384e452d (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461 1 lock held by rsyslogd/4453: 2 locks held by getty/4543: #0: 000000000398647e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000a1ed8f94 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4544: #0: 00000000c3146e20 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002038a537 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4545: #0: 00000000b48317ca (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c34a3452 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4546: #0: 00000000c22195a7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ed52955e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4547: #0: 000000006d3cf850 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000033583873 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4548: #0: 0000000049968fb6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000dd6bee5c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4549: #0: 000000003ff945f9 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000002e650076 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor2/4749: #0: 000000000d7f2e34 (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1554 [inline] #0: 000000000d7f2e34 (sb_writers#16){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 #1: 000000006a2e5013 (&sb->s_type->i_mutex_key#19){++++}, at: inode_lock include/linux/fs.h:715 [inline] #1: 000000006a2e5013 (&sb->s_type->i_mutex_key#19){++++}, at: chown_common+0x3a9/0x730 fs/open.c:640 2 locks held by syz-executor2/4815: #0: 000000000d7f2e34 (sb_writers#16){.+.+}, at: sb_start_write include/linux/fs.h:1554 [inline] #0: 000000000d7f2e34 (sb_writers#16){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 #1: 000000006a2e5013 (&sb->s_type->i_mutex_key#19){++++}, at: inode_lock include/linux/fs.h:715 [inline] #1: 000000006a2e5013 (&sb->s_type->i_mutex_key#19){++++}, at: chown_common+0x3a9/0x730 fs/open.c:640 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 902 Comm: khungtaskd Not tainted 4.18.0-rc4+ #139 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103 nmi_trigger_cpumask_backtrace+0x151/0x192 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:138 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x9c4/0xf80 kernel/hung_task.c:252 kthread+0x345/0x410 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 2419 Comm: udevd Not tainted 4.18.0-rc4+ #139 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0x76/0x5020 kernel/locking/lockdep.c:3294 Code: 00 00 00 48 c7 84 24 a0 00 00 00 b3 8a b5 41 48 c1 e8 03 48 89 84 24 90 00 00 00 48 01 d0 48 c7 84 24 a8 00 00 00 48 06 bf 88 <48> c7 84 24 b0 00 00 00 10 a8 5e 81 c7 00 f1 f1 f1 f1 c7 40 04 00 RSP: 0018:ffff8801ca0a6da0 EFLAGS: 00000082 RAX: ffffed0039414dc8 RBX: 1ffff10039414e30 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8801c9ce8a98 RBP: ffff8801ca0a7128 R08: 0000000000000001 R09: 0000000000000000 R10: ffff8801ca0a7658 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8801c9ce8a98 R14: ffff8801ca09a080 R15: 0000000000000000 FS: 00007f689d0587a0(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001ca7d2000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1e4/0x540 kernel/locking/lockdep.c:3924 __mutex_lock_common kernel/locking/mutex.c:757 [inline] __mutex_lock+0x176/0x1820 kernel/locking/mutex.c:894 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:909 ep_scan_ready_list+0xb77/0xf50 fs/eventpoll.c:681 ep_send_events fs/eventpoll.c:1706 [inline] ep_poll+0x3ef/0x1210 fs/eventpoll.c:1832 do_epoll_wait+0x1b0/0x200 fs/eventpoll.c:2190 __do_sys_epoll_wait fs/eventpoll.c:2200 [inline] __se_sys_epoll_wait fs/eventpoll.c:2197 [inline] __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2197 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f689c76c943 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:00007ffd949be138 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8 RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f689c76c943 RDX: 0000000000000008 RSI: 00007ffd949be230 RDI: 000000000000000a RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003 R13: 0000000000000000 R14: 00000000023b3430 R15: 00000000023b3250 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.264 msecs