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Date: Wed, 3 Apr 2024 17:25:10 -0400
From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: syzbot <syzbot+0cb5bb0f4bf9e79db3b3@syzkaller.appspotmail.com>,
        davem@davemloft.net, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org, luto@kernel.org, peterz@infradead.org,
        syzkaller-bugs@googlegroups.com, tglx@linutronix.de,
        Steffen Klassert <steffen.klassert@secunet.com>
Subject: Re: [PATCH] padata: Disable BH when taking works lock on MT path
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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@syzkaller.appspotmail.com
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>