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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Jann Horn References: <20261014171145.3292736-1-kas@kernel.org> <20261014171145.3292736-9-kas@kernel.org> From: Baolin Wang In-Reply-To: <20261014171145.3292736-9-kas@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 71CBD1C0003 X-Rspam-User: X-Stat-Signature: gxr3x873dyc58hojrdbntiy38q15abdi X-HE-Tag: 1792048920-372397 X-HE-Meta: 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 CRTs0AkG 4snhHtTbygXBEnpo/lfTugeCWfzKthObhH9KZTXnwujTxA591LMmTtYAwoKHFK5PFIRW4jtXDyAtelnpc5E3aZwydaoIeo4T8W6xltyWG6a0nqN7GUgqh7nuXzLO6tjGA4obFCE3mt46SSza91Cvm9CgJt843Hn2zJyuUe68yel5ErQ8uSpvG1f9cy+tb5ZClIUH04Eh8MSoC0aX6DQqGZmpKkSkPfRW0KcrFoHGnVcUOxZ6XEhHWUUbyvAyb6UoQDHIjiwu+C4puD0ocn0h+4//Ja5MMhqLpe77X2Qind0I5Js7aLdWw9LkFjTHC6iDkgf5O6XDwp5MjF7aiOt8yojSHGoYFr3bFNTr31mcK/MGk4Gt1gA78PWxxirRdMM73BzbKzj0OqeDEYNY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/15/26 1:11 AM, Kiryl Shutsemau (Meta) wrote: > collapse_scan_file() reads the page cache to decide whether a table is > worth collapsing and, when it is, calls collapse_file() itself. The > caller cannot get between the decision and the collapse. > > Move the collapse_file() call up into collapse_single_pmd(), so the scan > stops at the decision. > > Two things change with it. The writeback retry re-runs collapse_file() > alone instead of rescanning first; collapse_file() repeats the scan's > checks under the page cache lock anyway. And mm_khugepaged_scan_file > fires before the collapse, so for an accepted table its status reads > SCAN_SUCCEED; what the collapse made of the table is for > mm_khugepaged_collapse_file to report. > > Preparation for splitting a collapse into a scan under mmap_lock and a > run without it. The file scan has to stop where the anonymous one will. > > Assisted-by: LLM > Acked-by: David Hildenbrand (Arm) > Reviewed-by: Zi Yan > Signed-off-by: Kiryl Shutsemau (Meta) > --- LGTM. Reviewed-by: Baolin Wang