syzbot

INFO: task syz-executor2:7537 blocked for more than 120 seconds.
      Not tainted 4.17.0+ #83
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D20088  7537   4598 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2876 [inline]
 __schedule+0x801/0x1e30 kernel/sched/core.c:3518
 schedule+0xef/0x430 kernel/sched/core.c:3562
 io_schedule+0x1c/0x70 kernel/sched/core.c:5182
 __blkdev_direct_IO_simple+0x7fc/0xfb0 fs/block_dev.c:241
 blkdev_direct_IO+0xb46/0x10e0 fs/block_dev.c:428
 generic_file_read_iter+0x510/0x2f00 mm/filemap.c:2341
 blkdev_read_iter+0x120/0x190 fs/block_dev.c:1930
 call_read_iter include/linux/fs.h:1778 [inline]
 generic_file_splice_read+0x552/0x910 fs/splice.c:307
 do_splice_to+0x12e/0x190 fs/splice.c:880
 splice_direct_to_actor+0x268/0x8d0 fs/splice.c:952
 do_splice_direct+0x2cc/0x400 fs/splice.c:1061
 do_sendfile+0x60f/0xe00 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1495 [inline]
 __se_sys_sendfile64 fs/read_write.c:1487 [inline]
 __x64_sys_sendfile64+0x155/0x240 fs/read_write.c:1487
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a09
RSP: 002b:00007fb973522c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fb9735236d4 RCX: 0000000000455a09
RDX: 0000000020000040 RSI: 0000000000000013 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 000000001b7889b2 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000005a5 R14: 00000000006fd818 R15: 0000000000000000

Showing all locks held in the system:
2 locks held by khungtaskd/892:
 #0: 00000000a1a53a66 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0: 00000000a1a53a66 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249
 #1: 0000000058f20940 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470
1 lock held by rsyslogd/4431:
 #0: 00000000e5d9fe46 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1a9/0x1e0 fs/file.c:766
2 locks held by getty/4522:
 #0: 000000003c52e76d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000c44362cb (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4523:
 #0: 0000000092451c7b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000004ce25b6a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4524:
 #0: 00000000a43ecc6b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000009cafe530 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4525:
 #0: 000000004ebda64b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000007f560cf (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4526:
 #0: 000000005978dcf3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000fa86e638 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4527:
 #0: 000000000a3d4c4d (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000049dda11f (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4528:
 #0: 00000000ca136047 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000e2f99769 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 892 Comm: khungtaskd Not tainted 4.17.0+ #83
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+0x1b9/0x294 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 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:138 [inline]
 check_hung_task kernel/hung_task.c:132 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
 watchdog+0xc10/0xf60 kernel/hung_task.c:249
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
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:54