linux-kernel - Re: [next-20260108]kernel BUG at drivers/scsi/scsi

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Message-ID: <aWD7j3NR_m6EyZv1@fedora>
Date: Fri, 9 Jan 2026 20:58:55 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
Cc: Christoph Hellwig <hch@...radead.org>, linux-block@...r.kernel.org,
	linux-scsi@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
	James.Bottomley@...senpartnership.com, leonro@...dia.com,
	kch@...dia.com, LKML <linux-kernel@...r.kernel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>, riteshh@...ux.ibm.com,
	ojaswin@...ux.ibm.com
Subject: Re: [next-20260108]kernel BUG at drivers/scsi/scsi_lib.c:1173!

On Fri, Jan 09, 2026 at 05:51:15PM +0530, Venkat Rao Bagalkote wrote:
> 
> On 09/01/26 5:25 pm, Ming Lei wrote:
> > On Fri, Jan 09, 2026 at 05:14:36PM +0530, Venkat Rao Bagalkote wrote:
> > > On 09/01/26 12:19 pm, Ming Lei wrote:
> > > > On Thu, Jan 08, 2026 at 09:56:39PM -0800, Christoph Hellwig wrote:
> > > > > I've seen the same when running xfstests on xfs, and bisected it to:
> > > > > 
> > > > > commit ee623c892aa59003fca173de0041abc2ccc2c72d
> > > > > Author: Ming Lei <ming.lei@...hat.com>
> > > > > Date:   Wed Dec 31 11:00:55 2025 +0800
> > > > > 
> > > > >       block: use bvec iterator helper for bio_may_need_split()
> > > > > 
> > > > Hi Christoph and Venkat Rao Bagalkote,
> > > > 
> > > > Unfortunately I can't duplicate the issue in my environment, can you test
> > > > the following patch?
> > > > 
> > > > diff --git a/block/blk.h b/block/blk.h
> > > > index 98f4dfd4ec75..980eef1f5690 100644
> > > > --- a/block/blk.h
> > > > +++ b/block/blk.h
> > > > @@ -380,7 +380,7 @@ static inline bool bio_may_need_split(struct bio *bio,
> > > >                   return true;
> > > >           bv = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
> > > > -       if (bio->bi_iter.bi_size > bv->bv_len)
> > > > +       if (bio->bi_iter.bi_size > bv->bv_len - bio->bi_iter.bi_bvec_done)
> > > >                   return true;
> > > >           return bv->bv_len + bv->bv_offset > lim->max_fast_segment_size;
> > > >    }
> > > Hello Ming,
> > > 
> > > 
> > > This is not helping. I am hitting this issue, during kernel build itself.
> > Can you confirm if it can fix the blktests ext4/056 first?
> > 
> > If kernel building is running over new patched kernel, please provide the
> > dmesg log. And if it is reproduciable, can you confirm if it can be fixed
> > by reverting ee623c892aa59003 (block: use bvec iterator helper for bio_may_need_split())?
> 
> 
> Unfortunately, even with revert, build fails.
> 
> 
> 
> commit c64b2ee9cddcb31546c8622ef018d344544a9388 (HEAD)
> Author: Super User <root@...-zzci-1.ltc.tadn.ibm.com>
> Date:   Fri Jan 9 06:51:19 2026 -0600
> 
>     Revert "block: use bvec iterator helper for bio_may_need_split()"
> 
>     This reverts commit ee623c892aa59003fca173de0041abc2ccc2c72d.

OK, then your issue isn't related with the above change.

Can you reproduce & collect dmesg log with the bad sg/rq/bio/bvec info by
applying the attached debug patch?

Also if possible, please collect your scsi queue's limit info before
reproducing the issue:

	(cd /sys/block/$SD/queue && find . -type f -exec grep -aH . {} \;)



Thanks, 
Ming

View attachment "rq-dbg.patch" of type "text/plain" (3457 bytes)