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Message-ID: <20250903023326.6389-1-hdanton@sina.com>
Date: Wed, 3 Sep 2025 10:33:25 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+5b4f4f81240931b16844@...kaller.appspotmail.com>
Cc: linux-kernel@...r.kernel.org,
syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [block?] [mm?] INFO: rcu detected stall in wb_workfn (4)
> Date: Tue, 02 Sep 2025 07:41:28 -0700 [thread overview]
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: b320789d6883 Linux 6.17-rc4
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1406ae62580000
> 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
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5e34580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1639ca42580000
#syz test upstream master
--- x/kernel/rcu/tree_stall.h
+++ y/kernel/rcu/tree_stall.h
@@ -590,8 +590,15 @@ static void rcu_check_gp_kthread_starvat
if (cpu_is_offline(cpu)) {
pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu);
} else if (!(data_race(READ_ONCE(rdp->mynode->qsmask)) & rdp->grpmask)) {
+ int i;
pr_err("Stack dump where RCU GP kthread last ran:\n");
dump_cpu_task(cpu);
+ for_each_online_cpu(i) {
+ if (i == cpu)
+ continue;
+ pr_err("Stack dump on CPU%d\n", i);
+ dump_cpu_task(i);
+ }
}
wake_up_process(gpk);
}
--
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