syzbot

kworker/dying (3590) used greatest stack depth: 13056 bytes left
INFO: task syz-executor2:1547 blocked for more than 120 seconds.
      Not tainted 4.14.0+ #186
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D20800  1547  12422 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2799 [inline]
 __schedule+0x8eb/0x2060 kernel/sched/core.c:3375
 schedule+0xf5/0x430 kernel/sched/core.c:3434
 io_schedule+0x1c/0x70 kernel/sched/core.c:5042
 __blkdev_direct_IO_simple+0x760/0xef0 fs/block_dev.c:241
 blkdev_direct_IO+0xc8a/0x1000 fs/block_dev.c:428
 generic_file_read_iter+0x4d2/0x28f0 mm/filemap.c:2344
 blkdev_read_iter+0x105/0x170 fs/block_dev.c:1913
 call_read_iter include/linux/fs.h:1766 [inline]
 generic_file_splice_read+0x3ff/0x7c0 fs/splice.c:307
 do_splice_to+0x110/0x170 fs/splice.c:880
 splice_direct_to_actor+0x242/0x820 fs/splice.c:952
 do_splice_direct+0x2a7/0x3d0 fs/splice.c:1061
 do_sendfile+0x5d5/0xe90 fs/read_write.c:1413
 SYSC_sendfile64 fs/read_write.c:1468 [inline]
 SyS_sendfile64+0xbd/0x160 fs/read_write.c:1460
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452879
RSP: 002b:00007f782191ebe8 EFLAGS: 00000212 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879
RDX: 00000000200ddff8 RSI: 0000000000000014 RDI: 0000000000000014
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0008000100000001 R11: 0000000000000212 R12: 00000000006f5590
R13: 00000000ffffffff R14: 00007f782191f6d4 R15: 0000000000000000

Showing all locks held in the system:
2 locks held by khungtaskd/665:
 #0:  (rcu_read_lock){....}, at: [<ffffffff81709e65>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0:  (rcu_read_lock){....}, at: [<ffffffff81709e65>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249
 #1:  (tasklist_lock){.+.+}, at: [<ffffffff81550b23>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554
1 lock held by rsyslogd/2929:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff81b62581>] __fdget_pos+0x131/0x1a0 fs/file.c:770
2 locks held by getty/3012:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3013:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3014:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3015:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3016:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/3017:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
2 locks held by getty/18457:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff851023d7>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8285a842>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131

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

NMI backtrace for cpu 0
CPU: 0 PID: 665 Comm: khungtaskd Not tainted 4.14.0+ #186
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x122/0x180 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+0x90c/0xd60 kernel/hung_task.c:249
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:437
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:54