INFO: task syz-executor.0:8642 blocked for more than 143 seconds. Not tainted 5.5.0-rc7-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D24136 8642 1 0x00004004 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x87f/0xcd0 kernel/sched/core.c:4081 schedule+0x188/0x210 kernel/sched/core.c:4155 rwsem_down_write_slowpath+0x807/0xdc0 kernel/locking/rwsem.c:1238 __down_write kernel/locking/rwsem.c:1392 [inline] down_write+0x12b/0x140 kernel/locking/rwsem.c:1535 inode_lock include/linux/fs.h:791 [inline] vfs_unlink+0xdc/0x580 fs/namei.c:3930 do_unlinkat+0x36c/0x7c0 fs/namei.c:4003 __do_sys_unlink fs/namei.c:4050 [inline] __se_sys_unlink fs/namei.c:4048 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4048 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45b097 Code: af 55 fd ff 48 8b 44 24 18 48 89 04 24 e8 61 55 fd ff 48 8d 05 55 a6 4e 00 48 89 04 24 48 c7 44 24 08 0a 00 00 00 e8 88 55 fd 48 8b 44 24 10 48 89 04 24 e8 ba 53 fd ff e8 c5 4e fd ff e8 b0 RSP: 002b:00007ffc20d51e88 EFLAGS: 00000246 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000045b097 RDX: 00007ffc20d51ea0 RSI: 00007ffc20d51ea0 RDI: 00007ffc20d51f30 RBP: 0000000000000993 R08: 0000000000000000 R09: 0000000000000009 R10: 0000000000000003 R11: 0000000000000246 R12: 00007ffc20d52fc0 R13: 0000000000bc8940 R14: 0000000000000000 R15: 00007ffc20d52fc0 Showing all locks held in the system: 1 lock held by khungtaskd/1126: #0: ffffffff890d45c0 (rcu_read_lock){....}, at: rcu_lock_acquire+0x4/0x30 include/linux/rcupdate.h:207 2 locks held by getty/8602: #0: ffff8880a3af1090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000194b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8603: #0: ffff88808ee99090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019db2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8604: #0: ffff8880a6e47090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000195b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8605: #0: ffff8880a95e9090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019bb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8606: #0: ffff88809d2c8090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000199b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8607: #0: ffff8880a067c090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc9000197b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 2 locks held by getty/8608: #0: ffff888094921090 (&tty->ldisc_sem){++++}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:267 #1: ffffc900019132e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x22f/0x1bc0 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.0/8642: #0: ffff8880a8718428 (sb_writers#3){.+.+}, at: sb_start_write include/linux/fs.h:1650 [inline] #0: ffff8880a8718428 (sb_writers#3){.+.+}, at: mnt_want_write+0x4a/0xa0 fs/namespace.c:354 #1: ffff8880a56ea3c8 (&type->i_mutex_dir_key#3/1){+.+.}, at: inode_lock_nested include/linux/fs.h:826 [inline] #1: ffff8880a56ea3c8 (&type->i_mutex_dir_key#3/1){+.+.}, at: do_unlinkat+0x18b/0x7c0 fs/namei.c:3989 #2: ffff888091aa4648 (&sb->s_type->i_mutex_key#10){++++}, at: inode_lock include/linux/fs.h:791 [inline] #2: ffff888091aa4648 (&sb->s_type->i_mutex_key#10){++++}, at: vfs_unlink+0xdc/0x580 fs/namei.c:3930 2 locks held by syz-executor.0/28181: #0: ffff8880a8718428 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2885 [inline] #0: ffff8880a8718428 (sb_writers#3){.+.+}, at: vfs_write+0x24e/0x580 fs/read_write.c:557 #1: ffff888091aa4648 (&sb->s_type->i_mutex_key#10){++++}, at: inode_lock include/linux/fs.h:791 [inline] #1: ffff888091aa4648 (&sb->s_type->i_mutex_key#10){++++}, at: ext4_buffered_write_iter+0xa7/0x5e0 fs/ext4/file.c:246 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1126 Comm: khungtaskd Not tainted 5.5.0-rc7-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+0x1fb/0x318 lib/dump_stack.c:118 nmi_cpu_backtrace+0xaa/0x190 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x16f/0x290 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x10/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace+0x17/0x20 include/linux/nmi.h:146 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xd40/0xd60 kernel/hung_task.c:289 kthread+0x332/0x350 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60