INFO: task syz-executor2:12956 blocked for more than 140 seconds. Not tainted 4.19.0-rc8+ #286 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D23528 12956 5335 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 __rwsem_down_write_failed_common+0xbb9/0x1670 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_nested+0xa9/0x130 kernel/locking/rwsem.c:194 inode_lock_nested include/linux/fs.h:773 [inline] do_unlinkat+0x3d8/0xa30 fs/namei.c:4049 __do_sys_unlink fs/namei.c:4110 [inline] __se_sys_unlink fs/namei.c:4108 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4108 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457569 Code: 83 c4 18 c3 e8 d8 64 00 00 48 8b 04 24 48 8b 4c 24 08 48 89 01 e8 d7 2d fc ff e8 22 7a fc ff b8 02 00 00 00 48 8d 0d 2a 60 09 <01> 87 01 8b 05 22 60 09 01 83 f8 01 0f 85 8a 00 00 00 b8 01 00 00 RSP: 002b:00007ffa7e4cfc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000457569 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000300 RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffa7e4d06d4 R13: 00000000004c26a6 R14: 00000000004d8448 R15: 00000000ffffffff Showing all locks held in the system: 1 lock held by khungtaskd/983: #0: 00000000668ab395 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x424 kernel/locking/lockdep.c:4435 3 locks held by rs:main Q:Reg/5170: #0: 00000000dfc684d7 (&rq->lock){-.-.}, at: idle_balance kernel/sched/fair.c:9537 [inline] #0: 00000000dfc684d7 (&rq->lock){-.-.}, at: pick_next_task_fair+0x1091/0x16d0 kernel/sched/fair.c:6699 #1: 00000000668ab395 (rcu_read_lock){....}, at: __update_idle_core+0xc4/0x600 kernel/sched/fair.c:5950 #2: 00000000dd15592c (&sb->s_type->i_mutex_key#10){++++}, at: inode_trylock include/linux/fs.h:758 [inline] #2: 00000000dd15592c (&sb->s_type->i_mutex_key#10){++++}, at: ext4_file_write_iter+0x2a1/0x1420 fs/ext4/file.c:232 1 lock held by rsyslogd/5172: #0: 000000007756df4b (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/5262: #0: 00000000a43734c6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000de44da93 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5263: #0: 000000006f087086 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000044115871 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5264: #0: 00000000f39474b1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000cd3fb46b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5265: #0: 00000000802e853c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000002cc13b72 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5266: #0: 00000000e01e3cb1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000f00cd39a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5267: #0: 0000000052d27642 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000092ec2442 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/5268: #0: 00000000edf94bc0 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000064b0c27a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by syz-executor2/12904: #0: 00000000e35dd951 (sb_writers#13){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 00000000e35dd951 (sb_writers#13){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 0000000082bc475d (&sb->s_type->i_mutex_key#22/1){+.+.}, at: inode_lock_nested include/linux/fs.h:773 [inline] #1: 0000000082bc475d (&sb->s_type->i_mutex_key#22/1){+.+.}, at: do_unlinkat+0x3d8/0xa30 fs/namei.c:4049 2 locks held by syz-executor2/12956: #0: 00000000e35dd951 (sb_writers#13){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 00000000e35dd951 (sb_writers#13){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 0000000082bc475d (&sb->s_type->i_mutex_key#22/1){+.+.}, at: inode_lock_nested include/linux/fs.h:773 [inline] #1: 0000000082bc475d (&sb->s_type->i_mutex_key#22/1){+.+.}, at: do_unlinkat+0x3d8/0xa30 fs/namei.c:4049 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 983 Comm: khungtaskd Not tainted 4.19.0-rc8+ #286 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 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57