From: Thomas Gleixner <tglx@kernel.org>
To: syzbot <syzbot+123e1b70473ce213f3af@syzkaller.appspotmail.com>,
linux-kernel@vger.kernel.org, peterz@infradead.org,
syzkaller-bugs@googlegroups.com
Cc: Steffen Klassert <steffen.klassert@secunet.com>,
Daniel Jordan <daniel.m.jordan@oracle.com>
Subject: Re: [syzbot] [kernel?] WARNING in _cpu_down
Date: Wed, 11 Mar 2026 08:56:36 +0100 [thread overview]
Message-ID: <87sea6re8b.ffs@tglx> (raw)
In-Reply-To: <69af0a05.050a0220.310d8.002f.GAE@google.com>
On Mon, Mar 09 2026 at 10:57, syzbot wrote:
> syzbot found the following issue on:
>
> HEAD commit: 4ae12d8bd9a8 Merge tag 'kbuild-fixes-7.0-2' of git://git.k..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=177cca02580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=163cf0fb07ea84d3
> dashboard link: https://syzkaller.appspot.com/bug?extid=123e1b70473ce213f3af
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> smpboot: CPU 1 is now offline
> smpboot: Booting Node 0 Processor 1 APIC 0x1
> ------------[ cut here ]------------
> DEAD callback error for CPU1
> WARNING: kernel/cpu.c:1463 at _cpu_down+0x759/0x1020 kernel/cpu.c:1463, CPU#0: syz.0.1960/14614
That means one of the hotplug state callbacks which are issued after a
CPU is dead returned an error. That's wrong. Those callbacks are not
supposed to fail as there is no way to rollback at that point.
A quick coccinelle search finds exactly one callback in that stage which
might return an error code:
padata_cpu_dead()
Not sure how to fix that. I leave it to the padata folks ...
Thanks
tglx
next prev parent reply other threads:[~2026-03-11 7:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-09 17:57 [syzbot] [kernel?] WARNING in _cpu_down syzbot
2026-03-11 7:56 ` Thomas Gleixner [this message]
2026-03-11 16:45 ` Daniel Jordan
2026-03-12 17:45 ` Daniel Jordan
2026-03-17 3:52 ` syzbot
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