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Message-ID: <f37f8e60-d580-0b7c-0fa5-a26ab49c9781@kernel.dk>
Date:   Mon, 9 Jan 2023 20:18:39 -0700
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Subject: Re: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly
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To:     Yishai Hadas <yishaih@nvidia.com>, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, linux-mm@kvack.org, jgg@nvidia.com,
        logang@deltatee.com, Andrew Morton <akpm@linux-foundation.org>
Cc:     hch@lst.de, alex.williamson@redhat.com, leonro@nvidia.com,
        maorg@nvidia.com
References: <20230109144701.83021-1-yishaih@nvidia.com>
From:   Jens Axboe <axboe@kernel.dk>
In-Reply-To: <20230109144701.83021-1-yishaih@nvidia.com>
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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@kernel.dk>

Andrew, can you pick this one up?

-- 
Jens Axboe