Re: INFO: task hung in __blkdev_direct_IO_simple

[Dmitry Vyukov]

On Sun, Dec 10, 2017 at 2:38 PM, syzbot
<bot+351690c704439fdf063697b93591b48688cb9043@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> ad4dac17f9d563b9e34aab78a34293b10993e9b5
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
> Unfortunately, I don't have any reproducer for this bug yet.
>
>
> devpts: called with bogus options
> devpts: called with bogus options
> INFO: task syz-executor5:12140 blocked for more than 120 seconds.
>       Not tainted 4.15.0-rc2-next-20171208+ #63
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> syz-executor5   D20184 12140   3394 0x00000004
> Call Trace:
>  context_switch kernel/sched/core.c:2800 [inline]
>  __schedule+0x8eb/0x2060 kernel/sched/core.c:3376
>  schedule+0xf5/0x430 kernel/sched/core.c:3435
>  io_schedule+0x1c/0x70 kernel/sched/core.c:5043
>  __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:2343
>  blkdev_read_iter+0x105/0x170 fs/block_dev.c:1913
>  call_read_iter include/linux/fs.h:1770 [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: 0033:0x452a39
> RSP: 002b:00007fef259dec58 EFLAGS: 00000212 ORIG_RAX: 0000000000000028
> RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452a39
> RDX: 00000000208b2ff8 RSI: 0000000000000018 RDI: 0000000000000018
> RBP: 00000000000001f2 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000100000001 R11: 0000000000000212 R12: 00000000006f0f50
> R13: 00000000ffffffff R14: 00007fef259df6d4 R15: 0000000000000000
>
> Showing all locks held in the system:
> 2 locks held by khungtaskd/672:
>  #0:  (rcu_read_lock){....}, at: [<0000000017ead575>]
> check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
>  #0:  (rcu_read_lock){....}, at: [<0000000017ead575>] watchdog+0x1c5/0xd60
> kernel/hung_task.c:249
>  #1:  (tasklist_lock){.?.?}, at: [<00000000520b0338>]
> debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4554
> 2 locks held by getty/3115:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3116:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3117:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3118:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3119:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3120:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 2 locks held by getty/3121:
>  #0:  (&tty->ldisc_sem){++++}, at: [<0000000032ecb07b>]
> ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
>  #1:  (&ldata->atomic_read_lock){+.+.}, at: [<000000004dc20319>]
> n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2131
> 1 lock held by syz-executor1/12171:
>  #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<000000000f3ef86e>]
> lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355
> 1 lock held by syz-executor1/12177:
>  #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<000000000f3ef86e>]
> lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355
> 1 lock held by syz-executor1/12183:
>  #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<000000000f3ef86e>]
> lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355
> 1 lock held by syz-executor1/12186:
>  #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<000000000f3ef86e>]
> lo_ioctl+0x8b/0x1b90 drivers/block/loop.c:1355
>
> =============================================
>
> NMI backtrace for cpu 1
> CPU: 1 PID: 672 Comm: khungtaskd Not tainted 4.15.0-rc2-next-20171208+ #63
> 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:524
> Sending NMI from CPU 1 to CPUs 0:
> NMI backtrace for cpu 0
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc2-next-20171208+ #63
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> RIP: 0010:update_ts_time_stats+0x1/0x1c0 kernel/time/tick-sched.c:499
> RSP: 0018:ffff8801db207d18 EFLAGS: 00000046
> RAX: ffffffff8622f380 RBX: ffff8801db223540 RCX: 0000000000000000
> RDX: 00000039aafc2b88 RSI: ffff8801db223540 RDI: 0000000000000000
> RBP: ffff8801db207d48 R08: ffff88021fff801c R09: ffff88021fff8008
> R10: ffff88021fff8010 R11: ffff88021fff801d R12: ffff8801db2235a4
> R13: ffff8801db2235c0 R14: 00000039aafc2b88 R15: 0000000000000000
> FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000021d9000 CR3: 00000001d136c000 CR4: 00000000001426f0
> DR0: 0000000020000008 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
> Call Trace:
>  <IRQ>
>  irq_enter+0xbd/0xe0 kernel/softirq.c:346
>  scheduler_ipi+0x246/0x830 kernel/sched/core.c:1794
>  smp_reschedule_interrupt+0xe6/0x670 arch/x86/kernel/smp.c:277
>  reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:944
>  </IRQ>
> RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54
> RSP: 0018:ffffffff86207d08 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff02
> RAX: dffffc0000000000 RBX: 1ffffffff0c40fa4 RCX: 0000000000000000
> RDX: 1ffffffff0c5975c RSI: 0000000000000001 RDI: ffffffff862cbae0
> RBP: ffffffff86207d08 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: ffffffff86207dc0 R14: ffffffff869efaa0 R15: 0000000000000000
>  arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline]
>  default_idle+0xbf/0x430 arch/x86/kernel/process.c:355
>  arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346
>  default_idle_call+0x36/0x90 kernel/sched/idle.c:98
>  cpuidle_idle_call kernel/sched/idle.c:156 [inline]
>  do_idle+0x24a/0x3b0 kernel/sched/idle.c:246
>  cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351
>  rest_init+0xed/0xf0 init/main.c:436
>  start_kernel+0x729/0x74f init/main.c:717
>  x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
>  x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
>  secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237
> Code: 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 e8 c7 6b 0c 00 48 c7 c7 f0
> 94 60 81 e8 0b fc ff ff 5d c3 90 90 90 90 90 90 90 90 90 55 <48> 89 e5 41 57
> 41 56 41 55 41 54 49 89 f7 53 41 89 fd 49 89 d4

+loop maintainers

#syz dup: INFO: task hung in lo_ioctl

> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
>
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