Re: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly

From: Jason Gunthorpe
Date: Wed Jan 11 2023 - 08:33:06 EST


On Tue, Jan 10, 2023 at 04:03:47PM -0800, Andrew Morton wrote:
> On Mon, 9 Jan 2023 20:18:39 -0700 Jens Axboe <axboe@xxxxxxxxx> wrote:
>
> > On 1/9/23 7:47 AM, Yishai Hadas wrote:
> > > The last_pg is wrong, it is actually the first page of the last
> > > scatterlist element. To get the last page of the last scatterlist
> > > element we have to add prv->length. So it is checking mergability
> > > against the wrong page, Further, a SG element is not guaranteed to end
> > > on a page boundary, so we have to check the sub page location also for
> > > merge eligibility.
> > >
> > > Fix the above by checking physical contiguity, compute the actual last
> > > page and then call pages_are_mergable().
> >
> > Reviewed-by: Jens Axboe <axboe@xxxxxxxxx>
> >
> > Andrew, can you pick this one up?
>
> This patch is against Yishai's
>
> CommitDate: Thu Jan 5 16:01:05 2023 -0400
>
> lib/scatterlist: Fix to merge contiguous pages into the last SG properly
>
>
> which is in -next, apparently via a tree of Jason's. So I'll assume
> that Jason will handleit?

It is in v6.2-rc3 already, but sure I will take this too

Jason