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Miller" , Jesper Dangaard Brouer , Saeed Mahameed , Leon Romanovsky , Tariq Toukan , Andrew Lunn , Eric Dumazet , Paolo Abeni , Ilias Apalodimas , Simon Horman , Andrew Morton , Mina Almasry , Yonglong Liu , Yunsheng Lin , Pavel Begunkov , Matthew Wilcox , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH net-next v2 2/3] page_pool: Turn dma_sync and dma_sync_cpu fields into a bitmap Message-ID: <20250325151743.7ae425c3@kernel.org> In-Reply-To: <20250325-page-pool-track-dma-v2-2-113ebc1946f3@redhat.com> References: <20250325-page-pool-track-dma-v2-0-113ebc1946f3@redhat.com> <20250325-page-pool-track-dma-v2-2-113ebc1946f3@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 5FE8DA001E X-Stat-Signature: fyamwxnwa7y85onc5ptsk5u97mric5cb X-HE-Tag: 1742941084-954026 X-HE-Meta: U2FsdGVkX1/Eis3dq+FvJG46IDanlph016BH4aTqZ+KiBM61MSrtLX9MnQp/GQywKNitPGFDa9hO5LTwQn6UEfVGHNLVBrmwHfBODQCiiwmovpPOmAwXky3VeRxTN4rXFwBezSXAMijDtCVY0isIcvgbtZV1NOoADKGGZnkwMxs26Bt059xcud2WdtiyDAYt0PWj+JB2UHATtqkabUtFY7hfKG6/Suy+MzkH1ST90EGUA0rdQ6BnHuIG+w7MjFtFMhGeM078QvMbuBxAz2GqNvCrhcx6AgVkxNZYSxBigKkGk6d9iw9JxUM+fY+I7F6j0WkINpGWw6r3PjIdeAzrtHYSLZkoXQE3xuUhrKDsm62noYQ6mCFKJYF1aHsojRnARSRvGetJFkkazhXuG5+YuRpFuRlBdmKzrNz3n7oTBWskqpasqa70+t5p/1J4NmTNE+Ut/+fZuBUGUMZ60634s07F9wW/7sAYkTGwvvHENqq5dkIkYjgac8Zjz9HfCpuC2IBDuX8tDMBlvLX13ZMXoCSZKrLQgyzfXgOe8lpmhHgNoS7tpRYZ5cOoHA7AMw4XSLi0S7hbYls8RQ8s0VhWmdN3fa5rQpJF4X7kr0iOErb2YmQTfw3+1JPc0Dl61lX78ZVulskr0UYDHoXhSD5ulMZPx8tzjNv9WlIXqMme7gR38JSP9CUy3uWP1e88d09mptRrKUlxr2Ge8SV0+kBfrDL9zw/A97X7hYl2903eEDIRPcAnl/T6kcnrZcSLjnnKpS8qkNo/bXrg85v5obRX1T7MTMevo10wbHPnqqR8xVfaj1yypeOMO6/lO0gEsB+dfdy/68dvzEeAImwDoNhlJHIbEV9shNQQaPKunzcbmUMskGwIblWJDo463yn1OtSeK6FJ/xpcMayBUhi4DX3f98SQAgkew0aC+qp6snT8UoR+sUM6yFf1HK5gvOC/D12wzLtF2H7uCwH8XWGbwnt Vq/BeB0x MKd/vfKrsgacB+h68WVALuwWKrVubLOq3LdfTnVK5w8PnJII2yDtFrOK0o2ALNaliLn3KZEF/D+VlRdqZ/XJInxN9a86T/N2AedL4dyUbluJ9SZcNMn62AHg73DPTThI7ZVrZrGDIU3E3h33QLF6ybtJ3aYVAUKasa1yX0WINdc0gkaADDXMtuTVUOHC9azG0aPmWIjsqN92tG70UF2jdG79xNDbz7cRVA7P23aWplQAKpwpGewnqymZv0FBl1u7EiOQQecLrp8gjgLovrQVmIzML97i31WhnA139u6czZo28ILsIUjtEQGLKh8nm06bu3vf6pMmIwvSjtAyxi5saiMCi3Tmx+Rv1Gv+kwQgEPujQoMRNo85qZn1o/JaqYPle1+OS 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 Tue, 25 Mar 2025 16:45:43 +0100 Toke H=C3=B8iland-J=C3=B8rgensen wrote: > Change the single-bit booleans for dma_sync into an unsigned long with > BIT() definitions so that a subsequent patch can write them both with a > singe WRITE_ONCE() on teardown. Also move the check for the sync_cpu > side into __page_pool_dma_sync_for_cpu() so it can be disabled for > non-netmem providers as well. Can we make them just bools without the bit width? Less churn and actually fewer bytes. I don't see why we'd need to wipe them atomically. In fact I don't see why we're touching dma_sync_cpu, at all, it's driver-facing and the driver is gone in the problematic scenario.