INFO: task hung in pipe_read

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: bfb9e5c0 Linux 4.14.159
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1417ca8ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b2dd838381e2c80
dashboard link: https://syzkaller.appspot.com/bug?extid=d8a024467aae529327f3
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10bb9b46e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d8a024...@syzkaller.appspotmail.com

INFO: task syz-execprog:7090 blocked for more than 140 seconds.
Not tainted 4.14.159-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-execprog D27408 7090 7086 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
pipe_lock_nested fs/pipe.c:67 [inline]
pipe_lock fs/pipe.c:75 [inline]
pipe_wait+0x181/0x1a0 fs/pipe.c:123
pipe_read+0x4bc/0x810 fs/pipe.c:352
call_read_iter include/linux/fs.h:1771 [inline]
new_sync_read fs/read_write.c:401 [inline]
__vfs_read+0x4a4/0x6a0 fs/read_write.c:413
vfs_read+0x137/0x350 fs/read_write.c:447
SYSC_read fs/read_write.c:574 [inline]
SyS_read+0xfd/0x230 fs/read_write.c:567
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x47ea10
RSP: 002b:000000c42002fd88 EFLAGS: 00000212 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000047ea10
RDX: 0000000000010000 RSI: 000000c4204a6000 RDI: 0000000000000016
RBP: 000000c42002fde0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 000000c420164f50
R13: 0000000000000001 R14: 000000c420063b00 R15: 0000000000000001
INFO: task syz-executor.5:7530 blocked for more than 140 seconds.
Not tainted 4.14.159-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.5 D30000 7530 7113 0x00000000
Call Trace:
context_switch kernel/sched/core.c:2808 [inline]
__schedule+0x7b8/0x1cd0 kernel/sched/core.c:3384
schedule+0x92/0x1c0 kernel/sched/core.c:3428
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3486
__mutex_lock_common kernel/locking/mutex.c:833 [inline]
__mutex_lock+0x73c/0x1470 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
__pipe_lock fs/pipe.c:88 [inline]
pipe_write+0xb6/0xe40 fs/pipe.c:385
call_write_iter include/linux/fs.h:1777 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x4a7/0x6b0 fs/read_write.c:482
vfs_write+0x198/0x500 fs/read_write.c:544
SYSC_write fs/read_write.c:590 [inline]
SyS_write+0xfd/0x230 fs/read_write.c:582
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45a919
RSP: 002b:00007f2fb54abc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 000000010000000d RSI: 0000000020000000 RDI: 0000000000000000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2fb54ac6d4
R13: 00000000004cbe11 R14: 00000000004e5be8 R15: 00000000ffffffff

Showing all locks held in the system:
1 lock held by khungtaskd/1045:
#0: (tasklist_lock){.+.+}, at: [<ffffffff8148c8d8>]
debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4544
2 locks held by getty/7066:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7067:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7068:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7069:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7070:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7071:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
2 locks held by getty/7072:
#0: (&tty->ldisc_sem){++++}, at: [<ffffffff8664f9c3>]
ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376
#1: (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff83491bf6>]
n_tty_read+0x1e6/0x17d0 drivers/tty/n_tty.c:2156
1 lock held by syz-execprog/7090:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock
fs/pipe.c:75 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>]
pipe_wait+0x181/0x1a0 fs/pipe.c:123
1 lock held by syz-executor.5/7491:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock
fs/pipe.c:75 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>]
pipe_wait+0x181/0x1a0 fs/pipe.c:123
1 lock held by syz-executor.5/7530:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>] __pipe_lock
fs/pipe.c:88 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>]
pipe_write+0xb6/0xe40 fs/pipe.c:385
1 lock held by syz-executor.4/25283:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock
fs/pipe.c:75 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>]
pipe_wait+0x181/0x1a0 fs/pipe.c:123
1 lock held by syz-executor.3/28871:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock
fs/pipe.c:75 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>]
pipe_wait+0x181/0x1a0 fs/pipe.c:123
1 lock held by syz-executor.3/1760:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>] __pipe_lock
fs/pipe.c:88 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>]
pipe_write+0xb6/0xe40 fs/pipe.c:385
1 lock held by syz-executor.5/1762:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>] __pipe_lock
fs/pipe.c:88 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>]
pipe_write+0xb6/0xe40 fs/pipe.c:385
1 lock held by syz-executor.3/1764:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>] __pipe_lock
fs/pipe.c:88 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819165d6>]
pipe_write+0xb6/0xe40 fs/pipe.c:385
1 lock held by syz-executor.0/1765:
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock_nested
fs/pipe.c:67 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>] pipe_lock
fs/pipe.c:75 [inline]
#0: (&pipe->mutex/1){+.+.}, at: [<ffffffff819163c1>]
pipe_wait+0x181/0x1a0 fs/pipe.c:123

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

NMI backtrace for cpu 0
CPU: 0 PID: 1045 Comm: khungtaskd Not tainted 4.14.159-syzkaller #0
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+0x142/0x197 lib/dump_stack.c:58
nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x141/0x189 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:140 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline]
watchdog+0x5e7/0xb90 kernel/hung_task.c:274
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff866504ae


---
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