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Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1pEwZj-00BFfA-1g; Mon, 09 Jan 2023 11:08:48 -0700 Message-ID: Date: Mon, 9 Jan 2023 11:08:44 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Content-Language: en-CA To: Yishai Hadas , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, jgg@nvidia.com, axboe@kernel.dk Cc: hch@lst.de, alex.williamson@redhat.com, leonro@nvidia.com, maorg@nvidia.com References: <20230109144701.83021-1-yishaih@nvidia.com> From: Logan Gunthorpe In-Reply-To: <20230109144701.83021-1-yishaih@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: yishaih@nvidia.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, jgg@nvidia.com, axboe@kernel.dk, hch@lst.de, alex.williamson@redhat.com, leonro@nvidia.com, maorg@nvidia.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH] lib/scatterlist: Fix to calculate the last_pg properly X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) X-Rspam-User: X-Rspamd-Queue-Id: 0B2614000F X-Rspamd-Server: rspam01 X-Stat-Signature: tb3wqo7xp7p1qbu3pd4c5mffnn5z485g X-HE-Tag: 1673287730-287972 X-HE-Meta: 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 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 2023-01-09 07:47, 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(). > > Fixes: 1567b49d1a40 ("lib/scatterlist: add check when merging zone device pages") > Reported-by: Jason Gunthorpe > Signed-off-by: Yishai Hadas Looks right by my eye, thanks. Reviewed-by: Logan Gunthorpe Logan