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s=arc-20220608; d=hostedemail.com; t=1773204876; a=rsa-sha256; cv=none; b=aOeesS+KJuurLG822vITOkg8Ae22PwYwxBHTtx70lUSuU5yiud78FVePho/NIFYLbm3Cuq tF4Jpsh57Uw910p9ao9qfXh0DN04SEgiTSFvuaGNu4dMSXScs4tzzVZCVznB9SnbRBzsc+ pnNClCJZtLG9BlEs/B5R5WnOUZIyzSc= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf24.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 012A5165C; Tue, 10 Mar 2026 21:54:29 -0700 (PDT) Received: from [10.164.148.48] (unknown [10.164.148.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BEF5D3F73B; Tue, 10 Mar 2026 21:54:25 -0700 (PDT) Message-ID: <5de784bd-d9f9-4331-9e20-6e50f6510e3d@arm.com> Date: Wed, 11 Mar 2026 10:24:22 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/9] mm/rmap: make nr_pages signed in try_to_unmap_one To: Matthew Wilcox Cc: "David Hildenbrand (Arm)" , "Lorenzo Stoakes (Oracle)" , akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, hughd@google.com, chrisl@kernel.org, kasong@tencent.com, weixugc@google.com, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, youngjun.park@lge.com, ziy@nvidia.com, kas@kernel.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260310073013.4069309-1-dev.jain@arm.com> <20260310073013.4069309-2-dev.jain@arm.com> <21801fb7-0f42-4ad3-8b85-2ac6013b8aa5@lucifer.local> <31f93292-3de6-475c-b7fe-82ef41a3a7de@kernel.org> <04a7465b-ee69-479f-aaa4-ccdf3ae16805@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: ED557180005 X-Stat-Signature: 1677emig4b9coap7cyhfemetis765sjd X-Rspam-User: X-HE-Tag: 1773204875-727525 X-HE-Meta: U2FsdGVkX185NIsoYeZ6/ycTL7zgAK+TIH0qqOVU1hVfjlq/O+2QHga7rKaVO6b/dpUPdBjb6peZ53LCb+Lz/Fe9mO/s2qOAMdukj2QIeMeLrZ/o9R530cd86D9Q8X7R+lRDWpGfepIsuEEUeHLjmwo0SZtScuTFI8s83KbqI2Rvl6tCdqPzYkFd2ptPpaIYp3a5IylFjByd8sUIMWB+1V2a5B8gmmTpGvxQb0k+lVaR149qYQm+Ad4od8fP9J6mCofwHFgObjQ7kjzvedTpBdxsT8FvNGWqNAGpKCRfCkxE3Xh5NVrFGPGYKjRsLnbGIgSMYMnF5LqDM5K/dc+mj3g5AuFmvkEoHnayFbMCI6H26DMv23pjx/fUhy89BdCbNuDoTiPQf1cd5B7Og5GVKL7iuTmEvzrCk4yFtdLZIQF3govzlrzz4+RKok9/DtWZ4c0bcQF7rFSWbJMOE01nTFtftTSKYrIZGETYDc5nmBsaOyJZwU54GUPEnjGuQwrGAIIBCSQs6GyGXQltXr6GWbN0Ll12Ba38I9YW5an85OT8tk8HvQprLV67tM8E/PJszXd+fM9yDg7xKFCGBYUAd4UGKw2gqmSsWAMneZNn+M74lIEICo9x4p8IbLHMfweNhoy156fo7CAYV/B6wwe6nAsQGFf90rUvifl5HBUR4eVXhhTz3ctgUvkXgmliseynESmbYL399PVFkXpiMsSZ8NlPUYH8NoTzzgaw/2PkMJfGdd82sq2koMxiHpzIbeF25Htny8QmC/Dqs4qQbBlMwv7WNXSz53zOZcNKRkYiVQKl8Dw9nUkridEihnNVNCQbBmGgV1U86k0fGpATUkMPtl/hC2nB0lq4F22MEE+doj7vp0sldzqXfEyXstdOtlBUZcoaFpqjN/A= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/03/26 6:10 pm, Matthew Wilcox wrote: > On Tue, Mar 10, 2026 at 01:53:21PM +0530, Dev Jain wrote: >> So when I was playing around with the code, I noticed that passing >> unsigned int nr_pages to add_mm_counter(-nr_pages) messes up things. Then > > Using int (whether signed or unsigned) to store nr_pages is a bad idea. > Look how many people are asking about supporting PUD-sized folios. > On an ARM 64k PAGE_SIZE machine, that's 2^26 pages which is uncomfortably > close to 2^32. It'll only take one more level to exceed that, so, what, > five to ten more years? > > Just use unsigned long everywhere now and save ourselves the grief later. Thanks, let us do this.