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a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1673395428; bh=+OnFk+nK2FJmejEzbeXpqhqfabYhGoHiq3T5ktvxINM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=eImWOhdQkI/PtTOlc6FwsU5bJ5gZfkgokwiatUTAT5sSMZyzcc/5OG6Cj2FpYy0Ji uSo4fCT14oSdvWIMNNCrozckkzLwfFno3ogSovtwTkqsXEKV8vnqynwOIP0vQDdmZn N2/H0rokjq7tkxNGbfCUEYLaX6K/QD5d2SwopIR4= Date: Tue, 10 Jan 2023 16:03:47 -0800 From: Andrew Morton To: Jens Axboe Cc: Yishai Hadas , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, jgg@nvidia.com, logang@deltatee.com, hch@lst.de, alex.williamson@redhat.com, leonro@nvidia.com, maorg@nvidia.com Subject: Re: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly Message-Id: <20230110160347.c1d771e4ea21e4b95bfa8477@linux-foundation.org> In-Reply-To: References: <20230109144701.83021-1-yishaih@nvidia.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: D02A7180019 X-Stat-Signature: u9snh4tyf8whuaz1u9mq69fd85uzgzd3 X-HE-Tag: 1673395429-805909 X-HE-Meta: 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 g5ovMYfB hTUU0yJ/iINKjZ0fLObKAowqMRm2NBv4SNwsdzPjnvr4xdoFd/296VYNSR18hKl7amBt7zdo3gksQVELI1syzzr0gbc8/AzpKDVLq3n6EEULdF5FVOfVUtEbJ3A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, 9 Jan 2023 20:18:39 -0700 Jens Axboe 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 > > 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?