INFO: task hung in pipe_write

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 0238df646e62 Linux 4.19-rc7
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11ee025e400000
kernel config: https://syzkaller.appspot.com/x/.config?x=88e9a8a39dc0be2d
dashboard link: https://syzkaller.appspot.com/bug?extid=afac45302cedcb5a54ec
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+afac45...@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8e0dc3c6d4
R13: 00000000004c4f29 R14: 00000000004d8478 R15: 0000000000000003
ntfs: (device loop3): read_ntfs_boot_sector(): Primary boot sector is
invalid.
ntfs: (device loop3): read_ntfs_boot_sector(): Mount option errors=recover
not used. Aborting without trying to recover.
ntfs: (device loop3): ntfs_fill_super(): Not an NTFS volume.
INFO: task syz-executor4:5928 blocked for more than 140 seconds.
Not tainted 4.19.0-rc7+ #273
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4 D18936 5928 1 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2825 [inline]
__schedule+0x86c/0x1ed0 kernel/sched/core.c:3473
schedule+0xfe/0x460 kernel/sched/core.c:3517
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3575
__mutex_lock_common kernel/locking/mutex.c:1002 [inline]
__mutex_lock+0xbe7/0x1700 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
__pipe_lock fs/pipe.c:83 [inline]
pipe_write+0xc0/0xec0 fs/pipe.c:366
call_write_iter include/linux/fs.h:1808 [inline]
new_sync_write fs/read_write.c:474 [inline]
__vfs_write+0x6b8/0x9f0 fs/read_write.c:487
vfs_write+0x1fc/0x560 fs/read_write.c:549
ksys_write+0x101/0x260 fs/read_write.c:598
__do_sys_write fs/read_write.c:610 [inline]
__se_sys_write fs/read_write.c:607 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:607
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x410f70
Code: 48 ff c0 48 89 44 24 28 48 89 c1 48 c1 e0 0d 48 89 04 24 48 89 4c 24
08 e8 1d f1 00 00 0f b6 44 24 51 88 44 24 27 48 8d 0d 6d <4f> 0c 01 48 89
0c 24 48 8b 4c 24 28 48 89 4c 24 08 88 44 24 10 c6
RSP: 002b:00007ffe7e3e11d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000c RCX: 0000000000410f70
RDX: 000000000000000c RSI: 00007ffe7e3e1370 RDI: 0000000000000002
RBP: 00007ffe7e3e1370 R08: 0000000001e2c940 R09: 000000000000000c
R10: 0000000001e2c940 R11: 0000000000000246 R12: 000000000000000c
R13: 0000000000000001 R14: 000000000070bf20 R15: 0000000000000004
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 988 Comm: khungtaskd Not tainted 4.19.0-rc7+ #273
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+0x1c4/0x2b4 lib/dump_stack.c:113
nmi_cpu_backtrace.cold.3+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b3/0x1ed 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:144 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline]
watchdog+0xb3e/0x1050 kernel/hung_task.c:265
kthread+0x35a/0x420 kernel/kthread.c:246
ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
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:57


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.