INFO: task syz-executor2:7096 blocked for more than 140 seconds. Not tainted 4.18.0-rc7+ #170 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D24024 7096 4451 0x00000004 Call Trace: context_switch kernel/sched/core.c:2853 [inline] __schedule+0x87c/0x1ec0 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: 0033:0x456a09 Code: 24 00 00 00 e8 e8 4e fd ff 0f 0b e8 c1 34 00 00 e9 3c ff ff ff cc cc cc cc cc cc cc cc cc cc cc cc 64 48 8b 0c 25 f8 ff ff ff <48> 3b 61 10 76 40 48 83 ec 28 48 89 6c 24 20 48 8d 6c 24 20 48 8b RSP: 002b:00007f223a9d1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000005c RAX: ffffffffffffffda RBX: 00007f223a9d26d4 RCX: 0000000000456a09 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000140 RBP: 0000000000930320 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004ca580 R14: 00000000004c6b85 R15: 0000000000000004 Showing all locks held in the system: 1 lock held by khungtaskd/775: #0: 000000002840604f (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4461 1 lock held by rsyslogd/4315: 2 locks held by getty/4405: #0: 00000000b931d477 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000fa54984d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4406: #0: 000000001a474853 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000006caac3a2 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4407: #0: 000000001d414298 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000ade6e7ac (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4408: #0: 0000000055c97fa1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000001e1f0921 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4409: #0: 00000000dab66e7b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 000000007b9137b9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4410: #0: 00000000b8115b39 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 00000000c82fac2c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4411: #0: 00000000d00bab17 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 #1: 0000000031545115 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor2/7026: #0: 0000000060c6eaad (sb_writers#14){.+.+}, at: sb_start_write include/linux/fs.h:1554 [inline] #0: 0000000060c6eaad (sb_writers#14){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 #1: 000000009d8eb87b (&sb->s_type->i_mutex_key#17){+.+.}, at: inode_lock include/linux/fs.h:715 [inline] #1: 000000009d8eb87b (&sb->s_type->i_mutex_key#17){+.+.}, at: chown_common+0x3a9/0x730 fs/open.c:640 2 locks held by syz-executor2/7096: #0: 0000000060c6eaad (sb_writers#14){.+.+}, at: sb_start_write include/linux/fs.h:1554 [inline] #0: 0000000060c6eaad (sb_writers#14){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:386 #1: 000000009d8eb87b (&sb->s_type->i_mutex_key#17){+.+.}, at: inode_lock include/linux/fs.h:715 [inline] #1: 000000009d8eb87b (&sb->s_type->i_mutex_key#17){+.+.}, at: chown_common+0x3a9/0x730 fs/open.c:640 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 775 Comm: khungtaskd Not tainted 4.18.0-rc7+ #170 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 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54