linux-kernel - Re: [syzbot] [block?] [mm?] INFO: rcu detected stall in wb

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Message-ID: <68b7b203.050a0220.3db4df.01e4.GAE@google.com>
Date: Tue, 02 Sep 2025 20:12:03 -0700
From: syzbot <syzbot+5b4f4f81240931b16844@...kaller.appspotmail.com>
To: hdanton@...a.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [block?] [mm?] INFO: rcu detected stall in wb_workfn (4)

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in linkwatch_event

INFO: task kworker/u8:0:12 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0    state:D stack:24856 pid:12    tgid:12    ppid:2      task_flags:0x4208060 flags:0x00004000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1190/0x5de0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x81b/0x1060 kernel/locking/mutex.c:760
 linkwatch_event+0x51/0xc0 net/core/link_watch.c:303
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236


Tested on:

commit:         e6b9dce0 Merge tag 'sound-6.17-rc5' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13236e62580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d4703ac89d9e185a
dashboard link: https://syzkaller.appspot.com/bug?extid=5b4f4f81240931b16844
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15af4312580000