INFO: task syz-executor.2:7905 blocked for more than 143 seconds. Not tainted 5.1.0-rc6 #79 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D24176 7905 1 0x80000004 Call Trace: context_switch kernel/sched/core.c:2877 [inline] __schedule+0x813/0x1cc0 kernel/sched/core.c:3518 schedule+0x92/0x180 kernel/sched/core.c:3562 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3620 __mutex_lock_common kernel/locking/mutex.c:1002 [inline] __mutex_lock+0x726/0x1310 kernel/locking/mutex.c:1072 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087 acct_get kernel/acct.c:161 [inline] slow_acct_process kernel/acct.c:577 [inline] acct_process+0x2e5/0x61e kernel/acct.c:605 do_exit+0x17bd/0x2fa0 kernel/exit.c:866 do_group_exit+0x135/0x370 kernel/exit.c:980 get_signal+0x399/0x1d50 kernel/signal.c:2577 do_signal+0x87/0x1940 arch/x86/kernel/signal.c:816 exit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x412c6a Code: 0f 83 6a 18 00 00 c3 66 0f 1f 84 00 00 00 00 00 8b 05 2e 36 64 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d4 ff ff ff f7 RSP: 002b:00007fff8885f0f8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: fffffffffffffe00 RBX: 00000000021fa940 RCX: 0000000000412c6a RDX: 0000000040000000 RSI: 00007fff8885f130 RDI: ffffffffffffffff RBP: 0000000000000ac0 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff8885f130 R14: 00000000021fa99b R15: 00007fff8885f140 Showing all locks held in the system: 1 lock held by khungtaskd/1042: #0: 00000000845fe8c9 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5057 2 locks held by getty/7865: #0: 00000000755a1763 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000a6867b07 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7866: #0: 00000000e80f3790 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000008d80551e (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7867: #0: 00000000dd6e7e1f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000008be9c879 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7868: #0: 000000005d57a05e (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000005ae70358 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7869: #0: 00000000156c03e2 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000351c3a50 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7870: #0: 0000000069bb6cc7 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000fc83e87f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by getty/7871: #0: 000000006474d4a1 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000381c54a6 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.2/7905: #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 2 locks held by syz-executor.3/24836: #0: 000000009eddc8ff (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000022a015b9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/25119: #0: 0000000015b29722 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 0000000000d31284 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/25140: #0: 00000000b9cde3fd (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 00000000501a3e54 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/26370: #0: 000000001bc8d518 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 #1: 000000005bdb97b1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.2/1637: #0: 000000002defc21a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 #1: 000000001b54d834 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2825 [inline] #1: 000000001b54d834 (sb_writers#3){.+.+}, at: vfs_write+0x429/0x580 fs/read_write.c:548 #2: 0000000026bd58bb (&sb->s_type->i_mutex_key#9){++++}, at: inode_trylock include/linux/fs.h:792 [inline] #2: 0000000026bd58bb (&sb->s_type->i_mutex_key#9){++++}, at: ext4_file_write_iter+0x257/0x11c0 fs/ext4/file.c:232 3 locks held by syz-executor.2/1684: #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: acct_get kernel/acct.c:161 [inline] #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: slow_acct_process kernel/acct.c:577 [inline] #0: 0000000039ad07fa (&acct->lock#2){+.+.}, at: acct_process+0x2e5/0x61e kernel/acct.c:605 #1: 000000001b54d834 (sb_writers#3){.+.+}, at: file_start_write_trylock include/linux/fs.h:2832 [inline] #1: 000000001b54d834 (sb_writers#3){.+.+}, at: do_acct_process+0xf37/0x1150 kernel/acct.c:517 #2: 00000000bdf2d312 (&sb->s_type->i_mutex_key#9){++++}, at: inode_trylock include/linux/fs.h:792 [inline] #2: 00000000bdf2d312 (&sb->s_type->i_mutex_key#9){++++}, at: ext4_file_write_iter+0x257/0x11c0 fs/ext4/file.c:232 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1042 Comm: khungtaskd Not tainted 5.1.0-rc6 #79 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+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x63/0xa4 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1be/0x236 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:204 [inline] watchdog+0x9b7/0xec0 kernel/hung_task.c:288 kthread+0x357/0x430 kernel/kthread.c:253 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: