linux-kernel - Re: INFO: task hung in path

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Date:   Tue, 11 Jan 2022 03:39:01 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     cruise k <cruise4k@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        sunhao.th@...il.com, syzkaller@...glegroups.com
Subject: Re: INFO: task hung in path_openat

Dmitry,

Please stop syzbot from playing with the SCHED_FIFO setting.
We're being inundated with these useless bug reports.

On Tue, Jan 11, 2022 at 10:15:26AM +0800, cruise k wrote:
> Hi,
> 
> Syzkaller found the following issue:
> 
> HEAD commit: 75acfdb Linux 5.16-rc8
> git tree: upstream
> console output: https://pastebin.com/raw/7TSe1kGF
> kernel config: https://pastebin.com/raw/XsnKfdRt
> 
> And hope the report log can help you.
> 
> INFO: task systemd-udevd:27429 blocked for more than 146 seconds.
>       Not tainted 5.16.0-rc8+ #10
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:systemd-udevd   state:D stack:26528 pid:27429 ppid:  3127 flags:0x00000000
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:4972 [inline]
>  __schedule+0xcd9/0x2550 kernel/sched/core.c:6253
>  schedule+0xd2/0x260 kernel/sched/core.c:6326
>  rwsem_down_write_slowpath+0x664/0x1190 kernel/locking/rwsem.c:1151
>  __down_write_common kernel/locking/rwsem.c:1268 [inline]
>  __down_write_common kernel/locking/rwsem.c:1265 [inline]
>  __down_write kernel/locking/rwsem.c:1277 [inline]
>  down_write+0x135/0x150 kernel/locking/rwsem.c:1524
>  inode_lock include/linux/fs.h:783 [inline]
>  open_last_lookups fs/namei.c:3347 [inline]
>  path_openat+0xa66/0x26c0 fs/namei.c:3556
>  do_filp_open+0x1c1/0x290 fs/namei.c:3586
>  do_sys_openat2+0x61b/0x9a0 fs/open.c:1212
>  do_sys_open+0xc3/0x140 fs/open.c:1228
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fde8feb06f0
> RSP: 002b:00007ffdc8b61368 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fde8feb06f0
> RDX: 0000000000000180 RSI: 00000000000800c2 RDI: 00005624b8ca9880
> RBP: 000000000003a2f8 R08: 000000000000fefe R09: 00007fde8ff03740
> R10: 0000000000000000 R11: 0000000000000246 R12: 00005624b8ca9895
> R13: 8421084210842109 R14: 00000000000800c2 R15: 00007fde8ff3e540
>  </TASK>
> INFO: task systemd-udevd:27467 blocked for more than 148 seconds.
>       Not tainted 5.16.0-rc8+ #10
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:systemd-udevd   state:D stack:27072 pid:27467 ppid:  3127 flags:0x00000000
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:4972 [inline]
>  __schedule+0xcd9/0x2550 kernel/sched/core.c:6253
>  schedule+0xd2/0x260 kernel/sched/core.c:6326
>  rwsem_down_write_slowpath+0x664/0x1190 kernel/locking/rwsem.c:1151
>  __down_write_common kernel/locking/rwsem.c:1268 [inline]
>  __down_write_common kernel/locking/rwsem.c:1265 [inline]
>  __down_write kernel/locking/rwsem.c:1277 [inline]
>  down_write+0x135/0x150 kernel/locking/rwsem.c:1524
>  inode_lock include/linux/fs.h:783 [inline]
>  open_last_lookups fs/namei.c:3347 [inline]
>  path_openat+0xa66/0x26c0 fs/namei.c:3556
>  do_filp_open+0x1c1/0x290 fs/namei.c:3586
>  do_sys_openat2+0x61b/0x9a0 fs/open.c:1212
>  do_sys_open+0xc3/0x140 fs/open.c:1228
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fde8feb06f0
> RSP: 002b:00007ffdc8b60d78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fde8feb06f0
> RDX: 0000000000000180 RSI: 00000000000800c2 RDI: 00005624b8c989c0
> RBP: 000000000003a2f8 R08: 000000000000fcfe R09: 00007fde8ff03740
> R10: 0000000000000000 R11: 0000000000000246 R12: 00005624b8c989d6
> R13: 8421084210842109 R14: 00000000000800c2 R15: 00007fde8ff3e540
>  </TASK>
> INFO: task systemd-udevd:27515 blocked for more than 150 seconds.
>       Not tainted 5.16.0-rc8+ #10
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:systemd-udevd   state:D stack:27584 pid:27515 ppid:  3127 flags:0x00004000
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:4972 [inline]
>  __schedule+0xcd9/0x2550 kernel/sched/core.c:6253
>  schedule+0xd2/0x260 kernel/sched/core.c:6326
>  rwsem_down_write_slowpath+0x664/0x1190 kernel/locking/rwsem.c:1151
>  __down_write_common kernel/locking/rwsem.c:1268 [inline]
>  __down_write_common kernel/locking/rwsem.c:1265 [inline]
>  __down_write kernel/locking/rwsem.c:1277 [inline]
>  down_write+0x135/0x150 kernel/locking/rwsem.c:1524
>  inode_lock include/linux/fs.h:783 [inline]
>  open_last_lookups fs/namei.c:3347 [inline]
>  path_openat+0xa66/0x26c0 fs/namei.c:3556
>  do_filp_open+0x1c1/0x290 fs/namei.c:3586
>  do_sys_openat2+0x61b/0x9a0 fs/open.c:1212
>  do_sys_open+0xc3/0x140 fs/open.c:1228
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fde8feb06f0
> RSP: 002b:00007ffdc8b60d78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fde8feb06f0
> RDX: 0000000000000180 RSI: 00000000000800c2 RDI: 00005624b8cad110
> RBP: 000000000003a2f8 R08: 000000000000fefe R09: 00007fde8ff03740
> R10: 0000000000000000 R11: 0000000000000246 R12: 00005624b8cad126
> R13: 8421084210842109 R14: 00000000000800c2 R15: 00007fde8ff3e540
>  </TASK>
> INFO: task systemd-udevd:27530 blocked for more than 153 seconds.
>       Not tainted 5.16.0-rc8+ #10
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:systemd-udevd   state:D stack:26048 pid:27530 ppid:  3127 flags:0x00000000
> Call Trace:
>  <TASK>
>  context_switch kernel/sched/core.c:4972 [inline]
>  __schedule+0xcd9/0x2550 kernel/sched/core.c:6253
>  schedule+0xd2/0x260 kernel/sched/core.c:6326
>  rwsem_down_write_slowpath+0x664/0x1190 kernel/locking/rwsem.c:1151
>  __down_write_common kernel/locking/rwsem.c:1268 [inline]
>  __down_write_common kernel/locking/rwsem.c:1265 [inline]
>  __down_write kernel/locking/rwsem.c:1277 [inline]
>  down_write+0x135/0x150 kernel/locking/rwsem.c:1524
>  inode_lock include/linux/fs.h:783 [inline]
>  open_last_lookups fs/namei.c:3347 [inline]
>  path_openat+0xa66/0x26c0 fs/namei.c:3556
>  do_filp_open+0x1c1/0x290 fs/namei.c:3586
>  do_sys_openat2+0x61b/0x9a0 fs/open.c:1212
>  do_sys_open+0xc3/0x140 fs/open.c:1228
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7fde8feb06f0
> RSP: 002b:00007ffdc8b61368 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fde8feb06f0
> RDX: 0000000000000180 RSI: 00000000000800c2 RDI: 00005624b8ca9880
> RBP: 000000000003a2f8 R08: 000000000000fefe R09: 00007fde8ff03740
> R10: 0000000000000000 R11: 0000000000000246 R12: 00005624b8ca9896
> R13: 8421084210842109 R14: 00000000000800c2 R15: 00007fde8ff3e540
>  </TASK>