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[67.164.59.41]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7b9e3f288b1sm1168801b3a.7.2025.11.13.10.24.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Nov 2025 10:24:29 -0800 (PST) Date: Thu, 13 Nov 2025 10:24:27 -0800 From: "Vishal Moola (Oracle)" To: "Matthew Wilcox (Oracle)" Cc: Andrew Morton , David Hildenbrand , linux-mm@kvack.org Subject: Re: [PATCH 1/4] mm: Use frozen pages for page tables Message-ID: References: <20251113140448.1814860-1-willy@infradead.org> <20251113140448.1814860-2-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251113140448.1814860-2-willy@infradead.org> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C500A180019 X-Stat-Signature: 6yk4n9ryu3mkt1xqico1a3guxxwt37zw X-Rspam-User: X-HE-Tag: 1763058271-377321 X-HE-Meta: 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 egLibOZw K+5jK1iOtyJX3TGCU7jI4EK1/t9hqR9dv4aUijkS/mPywPv7Qx5fYOy9UTkHvrnShAROVxVm5zo90yFS1RfvwLJcl2bXp7MQ4vNDfO0mhVzovVoK0AG8n6+A8YyxQO/KZhjXd+U0sgBlKnmwdANFSlQX2o7m2tXyfA3UZxarfQNoyOM0RMpiWo4ZHvAOy2Zwge0EcvZQGfHq1izwFGuNvty3n+C2nvKhgcACNay9dFM9WbxvwVGoPHAAET0SGR0XgfivQ9mTTx+/ODB+dNQsdawugYMDzb3BVZ094ty9MdRwd0j5HMxYcd+/teI2MUWaee7F8NjxVpZ4+V++zj98erBJpZTrvXLfL6+2VIuK4OPMJDC1b7s41L+MRSRIobl1aEf7qwhu6m2unTB32azeXexeLDZJ42RST9QrCuPd8w1ianoDFlO9rWRLkLYbmekBeH09WH+98HI3yKeQF3U/spS7tgYwqXPCpPGbmw3u2H5hxnY5cxdKI6rSOCbLfCW8rurWaCQY+ACesuzubea1FSDLWqnw1PAwXh7e6b6LpwMzbArpOgsEHTavywiIwyamr9iAx 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 Thu, Nov 13, 2025 at 02:04:43PM +0000, Matthew Wilcox (Oracle) wrote: > Page tables do not use the reference count. That means we can avoid > two atomic operations (one on alloc, one on free) by allocating frozen > pages here. This does not interfere with compaction as page tables are > non-movable allocations. > > pagetable_alloc() and pagetable_free() need to move out of line to make > this work as alloc_frozen_page() and free_frozen_page() are not exported Nit: s/page/pages/g > outside the mm for now. We'll want them out of line anyway soon. > > Signed-off-by: Matthew Wilcox (Oracle) LGTM. Reviewed-by: Vishal Moola (Oracle)