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b=V5J3z3ATIEcEvlbOLsT8GbVOrIOvawcOkq9AXrlxBSdltJGZMpXCPOFEeBsOLClB7 BXnaFOBlXKGt6kKSmxPvhroGatW0qIklOx+S1V5KixSvt7LsnGbsiAgd0Ol8npJrKz wmF+jnhpFIC9+CAoqDse16mUrEZV+IrpkN5yYl6LcV75ixsayuFBHIiyu7DfkBqV7k zr9GYFC1cuAAkNmTGxW3eIYCYLSZnEPk9jcp+7sLHXxwov8SKsw96/pWmFp5q4G08D L05BjqvUQcR4XrWcTR/AW2/jDctdwdVyWqif6ZLldJH89xf03ltiY5vCaoLFukBdAr sxb2Yy1Auixog== Message-ID: <3b95bb12-5642-443b-b163-8b5f5f6400c4@kernel.org> Date: Mon, 9 Feb 2026 17:06:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/page_alloc: clear page->private in free_pages_prepare() To: Zi Yan Cc: Vlastimil Babka , Mikhail Gavrilov , linux-mm@kvack.org, akpm@linux-foundation.org, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, npiggin@gmail.com, linux-kernel@vger.kernel.org, kasong@tencent.com, hughd@google.com, chrisl@kernel.org, ryncsn@gmail.com, stable@vger.kernel.org, willy@infradead.org References: <209207FE-D3A9-4BE2-8DA7-9BE38A19F387@nvidia.com> <20260207173615.146159-1-mikhail.v.gavrilov@gmail.com> <51f96b31-fb59-4cda-9d33-e3cebc45686b@kernel.org> <42b977d1-4873-4b3e-9107-7055836cde11@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 2944120015 X-Stat-Signature: yxxhdhquh7p73xhno34d13gizy35gmqh X-Rspam-User: X-HE-Tag: 1770653209-345073 X-HE-Meta: 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 h5jAbQA9 NQijop8dK2i+t8hEhNh7hKaxuYVXw/0nbmBEqp8imUcWQ1WJvg9tPhMnRtnI3R4UYQzjXzxNti+HPuxIAUIqBwpBp/O7FGS7PXPZXIf8dNzceTKuaFsrj6XotfyYf/ciDqXNC5p7YHuSpKY10m+MD0NoBG19HicLCWFKrZ0JJZt9hOlbb3I9xLjlstf78xSv3LaREIepNsPIp6F5Z/CDIoFLOWwmLYXZRXjJhu2Bx0Z1IJ6qVKg/ylIWRyUMpRr3zBLsYFi1njxdiHm7xICbt8AfWEdxgXeDzdj3QchYRiKu410NUAESSWmTVcxMgEWctylb4qL8evyl1VyywdTj2uo9JGtAGYjlUsJbubdKNwtVdj+oDkkghw1QNbUdjTii4WQJZvoG8xZlua0s28QMkjfyU3g== 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 2/9/26 17:05, Zi Yan wrote: > On 9 Feb 2026, at 11:03, David Hildenbrand (Arm) wrote: > >> On 2/9/26 17:00, Zi Yan wrote: >>> >>> >>> Currently, _mm_id (_mm_ids) overlaps with page->private. At split time, >>> it should be MM_ID_DUMMY (0), so page->private should be 0 all time. >> >> Yes, it's designed like that; because that check here caught it during development :) >> >>> >>> >>> It is still better to have the check and fix in place. Why do we want to >>> skip device private folio? >> >> I don't understand the question, can you elaborate? > > You said, > “BTW, I wonder whether we should bring that check back for non-device folios.” > > I thought you know why device folio needs to keep ->private not cleared during > split. Oh, I thought there was some overlay of ->private with zone-device special stuff. But I checked the structs and didn't spot it immediately. So I ended up asking Balbir as reply to his latest series that got merged. -- Cheers, David