INFO: task syz-executor1:4695 blocked for more than 140 seconds. Not tainted 4.19.0-rc2+ #220 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor1 D21560 4695 1 0x00000004 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 __rwsem_down_write_failed_common+0x98b/0x1650 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:738 [inline] vfs_unlink+0xd1/0x510 fs/namei.c:3991 do_unlinkat+0x6cc/0xa30 fs/namei.c:4063 __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: 0033:0x456de7 Code: 31 00 00 00 e8 0a 4b fd ff 0f 0b e8 e3 30 00 00 e9 fe fe ff ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 64 48 8b 0c 25 f8 ff ff 48 3b 61 10 0f 86 ac 00 00 00 48 83 ec 28 48 89 6c 24 20 48 RSP: 002b:00007fff3b64d4e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000456de7 RDX: 00007fff3b64d500 RSI: 00007fff3b64d590 RDI: 00007fff3b64d590 RBP: 00000000000001ce R08: 0000000000000000 R09: 000000000000000a R10: 0000000000000005 R11: 0000000000000206 R12: 00007fff3b64e5f0 R13: 0000000000fbf940 R14: 0000000000000000 R15: badc0ffeebadface Showing all locks held in the system: 1 lock held by khungtaskd/792: #0: 00000000fcd96651 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4436 1 lock held by rsyslogd/4555: 2 locks held by getty/4646: #0: 000000003ecf8f64 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000058292b6e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4647: #0: 0000000045e23ad6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000b07a6587 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4648: #0: 0000000072b1e60f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000008cdbd9dc (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4649: #0: 000000006f539847 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000002fa521d4 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4650: #0: 0000000091c0520d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000026c5cad (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4651: #0: 00000000f437e48f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000cf511540 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4652: #0: 00000000da2bfb9c (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000006be44a2c (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 3 locks held by syz-executor1/4695: #0: 00000000a769e484 (sb_writers#5){.+.+}, at: sb_start_write include/linux/fs.h:1566 [inline] #0: 00000000a769e484 (sb_writers#5){.+.+}, at: mnt_want_write+0x3f/0xc0 fs/namespace.c:360 #1: 00000000649dfea0 (&type->i_mutex_dir_key/1){+.+.}, at: inode_lock_nested include/linux/fs.h:773 [inline] #1: 00000000649dfea0 (&type->i_mutex_dir_key/1){+.+.}, at: do_unlinkat+0x3d8/0xa30 fs/namei.c:4049 #2: 00000000aaecac72 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock include/linux/fs.h:738 [inline] #2: 00000000aaecac72 (&sb->s_type->i_mutex_key#13){+.+.}, at: vfs_unlink+0xd1/0x510 fs/namei.c:3991 3 locks held by syz-executor1/8169: #0: 00000000c520f586 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 #1: 00000000a769e484 (sb_writers#5){.+.+}, at: file_start_write include/linux/fs.h:2758 [inline] #1: 00000000a769e484 (sb_writers#5){.+.+}, at: vfs_write+0x42a/0x560 fs/read_write.c:548 #2: 00000000aaecac72 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_trylock include/linux/fs.h:758 [inline] #2: 00000000aaecac72 (&sb->s_type->i_mutex_key#13){+.+.}, at: ext4_file_write_iter+0x2a1/0x1450 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 792 Comm: khungtaskd Not tainted 4.19.0-rc2+ #220 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.3+0x48/0x88 lib/nmi_backtrace.c:101 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb39/0x1040 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 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57