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WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.69.30.204] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: B552E8002E X-Stat-Signature: pxqfd81bngs7kjkeug8z1tubzdd4ho3m X-Rspam-User: X-HE-Tag: 1700133007-425579 X-HE-Meta: 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 4h/AXYbg gHwaagEiEwPC6a/5nsEZEEx5rBt8ER5DcfNHO9w6vZvGmfIgq4tLp9AQ9SkVO2lvpCHaHi2Ia+Ndk8UQ+JXs+HdKyi0UQB+UyriH5TFFaUwJgoc8y0H6pmMk45fji3tF5qgwJtLe89L+oYyY= 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: List-Subscribe: List-Unsubscribe: On 2023/11/15 21:38, Jason Gunthorpe wrote: > On Wed, Nov 15, 2023 at 05:21:02PM +0800, Yunsheng Lin wrote: > >>>>> I would expect net stack, page pool, driver still see the 'struct page', >>>>> only memory provider see the specific struct for itself, for the above, >>>>> devmem memory provider sees the 'struct page_pool_iov'. >>>>> >>>>> The reason I still expect driver to see the 'struct page' is that driver >>>>> will still need to support normal memory besides devmem. >>> >>> I wouldn't say this approach is unreasonable, but it does have to be >>> done carefully to isolate the mm. Keeping the struct page in the API >>> is going to make this very hard. >> >> I would expect that most of the isolation is done in page pool, as far as >> I can see: > > It is the sort of thing that is important enough it should have > compiler help via types to prove that it is being done > properly. Otherwise it will be full of mistakes over time. Yes, agreed. I have done something similar as willy has done for some of folio conversion as below: +#define PAGE_POOL_MATCH(pg, iov) \ + static_assert(offsetof(struct page, pg) == \ + offsetof(struct page_pool_iov, iov)) +PAGE_POOL_MATCH(flags, res0); +PAGE_POOL_MATCH(pp_magic, pp_magic); +PAGE_POOL_MATCH(pp, pp); ... Not sure if we need to add new API for driver to use when the driver need the devmem support yet. > > Jason > . >