linux-kernel - [syzbot] INFO: task hung in kernfs_dop

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Message-ID: <00000000000042d02d05e2003028@google.com>
Date:   Tue, 21 Jun 2022 19:35:21 -0700
From:   syzbot <syzbot+41424c58d8613bce38c0@...kaller.appspotmail.com>
To:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, tj@...nel.org
Subject: [syzbot] INFO: task hung in kernfs_dop_revalidate

Hello,

syzbot found the following issue on:

HEAD commit:    f0ec9c65a8d6 Merge tag 'char-misc-5.19-rc3' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1012c290080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=70e1a4d352a3c6ae
dashboard link: https://syzkaller.appspot.com/bug?extid=41424c58d8613bce38c0
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17cdda40080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+41424c58d8613bce38c0@...kaller.appspotmail.com

INFO: task udevd:2979 blocked for more than 147 seconds.
      Not tainted 5.19.0-rc2-syzkaller-00147-gf0ec9c65a8d6 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:26640 pid: 2979 ppid:     1 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5116 [inline]
 __schedule+0xa00/0x4b30 kernel/sched/core.c:6428
 schedule+0xd2/0x1f0 kernel/sched/core.c:6500
 rwsem_down_read_slowpath+0x5b9/0xb00 kernel/locking/rwsem.c:1077
 __down_read_common kernel/locking/rwsem.c:1242 [inline]
 __down_read kernel/locking/rwsem.c:1251 [inline]
 down_read+0xe2/0x440 kernel/locking/rwsem.c:1491
 kernfs_dop_revalidate+0xec/0x600 fs/kernfs/dir.c:1098
 d_revalidate fs/namei.c:848 [inline]
 d_revalidate fs/namei.c:845 [inline]
 lookup_fast+0x385/0x6d0 fs/namei.c:1662
 walk_component+0xcf/0x6a0 fs/namei.c:2010
 link_path_walk.part.0+0x7ef/0xf70 fs/namei.c:2341
 link_path_walk fs/namei.c:2265 [inline]
 path_lookupat+0xc8/0x860 fs/namei.c:2492
 filename_lookup+0x1c6/0x590 fs/namei.c:2522
 user_path_at_empty+0x42/0x60 fs/namei.c:2895
 do_readlinkat+0xcd/0x2f0 fs/stat.c:456
 __do_sys_readlink fs/stat.c:489 [inline]
 __se_sys_readlink fs/stat.c:486 [inline]
 __x64_sys_readlink+0x74/0xb0 fs/stat.c:486
 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+0x46/0xb0
RIP: 0033:0x7fb1d2b27277
RSP: 002b:00007ffda1230de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 00007ffda1230df8 RCX: 00007fb1d2b27277
RDX: 0000000000000400 RSI: 00007ffda1230df8 RDI: 00007ffda12312d8
RBP: 0000000000000400 R08: 00000000007fffff R09: 0000563248ae65a0
R10: 00007fb1d2bb4fc0 R11: 0000000000000246 R12: 00007ffda12312d8
R13: 00007ffda1231248 R14: 0000563248ad0910 R15: 0000000000000000
 </TASK>
INFO: task syz-executor.3:3686 blocked for more than 156 seconds.
      Not tainted 5.19.0-rc2-syzkaller-00147-gf0ec9c65a8d6 #0


---
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