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Date:   Mon, 16 Jan 2023 12:10:23 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Yishai Hadas <yishaih@nvidia.com>
Cc:     linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-mm@kvack.org, axboe@kernel.dk, logang@deltatee.com,
        akpm@linux-foundation.org, willy@infradead.org, hch@lst.de,
        alex.williamson@redhat.com, leonro@nvidia.com, maorg@nvidia.com
Subject: Re: [PATCH V1] lib/scatterlist: Fix to calculate the last_pg properly
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References: <20230111101054.188136-1-yishaih@nvidia.com>
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On Wed, Jan 11, 2023 at 12:10:54PM +0200, 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 based on PFNs, compute the
> actual last page and then call pages_are_mergable().
> 
> Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages")
> Reported-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>

Applied to rdma for-rc

Thanks,
Jason