INFO: task syz-executor.3:9125 blocked for more than 143 seconds. Not tainted 5.5.0-rc1-next-20191213-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D24280 9125 1 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 rwsem_down_write_slowpath+0x6e8/0xf80 kernel/locking/rwsem.c:1238 __down_write kernel/locking/rwsem.c:1392 [inline] down_write+0x13c/0x150 kernel/locking/rwsem.c:1535 inode_lock include/linux/fs.h:791 [inline] vfs_unlink+0xd5/0x620 fs/namei.c:4125 do_unlinkat+0x3f7/0x6d0 fs/namei.c:4198 __do_sys_unlink fs/namei.c:4245 [inline] __se_sys_unlink fs/namei.c:4243 [inline] __x64_sys_unlink+0x42/0x50 fs/namei.c:4243 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a657 Code: 8d ac 24 00 10 00 00 48 8b 59 20 48 85 db 75 67 48 8b b4 24 20 10 00 00 8b 8c 24 28 10 00 00 48 89 e7 f3 a4 48 8b 94 24 18 10 <00> 00 ff 12 48 8b 94 24 10 10 00 00 48 8b bc 24 20 10 00 00 8b 8c RSP: 002b:00007fff281bd818 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045a657 RDX: 00007fff281bd830 RSI: 00007fff281bd830 RDI: 00007fff281bd8c0 RBP: 0000000000000040 R08: 0000000000000000 R09: 0000000000000008 R10: 0000000000000003 R11: 0000000000000246 R12: 00007fff281be950 R13: 0000000001547940 R14: 0000000000000000 R15: 00007fff281be950 Showing all locks held in the system: 3 locks held by kworker/u4:1/21: #0: ffff8880ae837518 (&rq->lock){-.-.}, at: newidle_balance+0xa28/0xe80 kernel/sched/fair.c:10166 #1: ffffffff899afa00 (rcu_read_lock){....}, at: __update_idle_core+0x45/0x3f0 kernel/sched/fair.c:5729 #2: ffff8880ae827418 (&base->lock){-.-.}, at: lock_timer_base+0x56/0x1b0 kernel/time/timer.c:936 1 lock held by khungtaskd/1116: #0: ffffffff899afa00 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/8987: #0: ffff88809ac31420 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/9077: #0: ffff88809e893090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000177b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9078: #0: ffff88809cbce090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000178b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9079: #0: ffff8880974c6090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000174b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9080: #0: ffff8880977bb090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000173b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9081: #0: ffff8880a0b2d090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000176b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9082: #0: ffff8880a313f090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000170b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9083: #0: ffff8880a8172090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900016cb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.3/9125: #0: ffff8880990c0428 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1649 [inline] #0: ffff8880990c0428 (sb_writers#3){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:354 #1: ffff888092ffc448 (&type->i_mutex_dir_key#3/1){+.+.}, at: inode_lock_nested include/linux/fs.h:826 [inline] #1: ffff888092ffc448 (&type->i_mutex_dir_key#3/1){+.+.}, at: do_unlinkat+0x29f/0x6d0 fs/namei.c:4184 #2: ffff8880a1b6c6c8 (&sb->s_type->i_mutex_key#11){++++}, at: inode_lock include/linux/fs.h:791 [inline] #2: ffff8880a1b6c6c8 (&sb->s_type->i_mutex_key#11){++++}, at: vfs_unlink+0xd5/0x620 fs/namei.c:4125 2 locks held by syz-executor.3/9652: #0: ffff8880990c0428 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2884 [inline] #0: ffff8880990c0428 (sb_writers#3){.+.+}, at: vfs_write+0x485/0x5d0 fs/read_write.c:557 #1: ffff8880a1b6c6c8 (&sb->s_type->i_mutex_key#11){++++}, at: inode_lock include/linux/fs.h:791 [inline] #1: ffff8880a1b6c6c8 (&sb->s_type->i_mutex_key#11){++++}, at: ext4_buffered_write_iter+0xba/0x460 fs/ext4/file.c:246 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1116 Comm: khungtaskd Not tainted 5.5.0-rc1-next-20191213-syzkaller #0 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+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:249 [inline] watchdog+0xdf1/0x14e0 kernel/hung_task.c:333 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60