Re: [PATCH] padata: Disable BH when taking works lock on MT path
From: Daniel Jordan
Date: Wed Apr 03 2024 - 17:25:45 EST
On Wed, Apr 03, 2024 at 05:36:18PM +0800, Herbert Xu wrote:
> On Mon, Apr 01, 2024 at 07:08:28AM -0700, syzbot wrote:
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 18737353cca0 Merge tag 'edac_urgent_for_v6.9_rc2' of git:/..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=15d605e5180000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=f64ec427e98bccd7
> > dashboard link: https://syzkaller.appspot.com/bug?extid=0cb5bb0f4bf9e79db3b3
> > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>
> Strictly speaking this can't happen because for the time being
> padata_do_multithreaded cannot run at the same time as the old
> padata which occurs in BH context.
>
> But the simplest fix is to just disable BH:
>
> ---8<---
> As the old padata code can execute in softirq context, disable
> softirqs for the new padata_do_mutithreaded code too as otherwise
> lockdep will get antsy.
>
> Reported-by: syzbot+0cb5bb0f4bf9e79db3b3@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Acked-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>