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Fri, 2 Oct 2026 07:08:12 -0400 (EDT) Date: Fri, 2 Oct 2026 12:08:11 +0100 From: Kiryl Shutsemau To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com, "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Jann Horn Subject: Re: [PATCH v4 08/13] mm/collapse: call collapse_file() from collapse_single_pmd() Message-ID: References: <20260928100630.21870-1-kirill@shutemov.name> <20260928100630.21870-9-kirill@shutemov.name> <67034af3-9849-49ab-8904-6d661178222f@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <67034af3-9849-49ab-8904-6d661178222f@kernel.org> On Thu, Oct 01, 2026 at 10:08:09AM +0200, David Hildenbrand (Arm) wrote: > On 9/28/26 12:06, Kiryl Shutsemau wrote: > > From: "Kiryl Shutsemau (Meta)" > > > > 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. > > That change wasn't actually required for "call collapse_file() from > collapse_single_pmd()", right? You merely decided to move the retry label in the > same patch. Yep. Once collapse_file() is called from here the retry can go around the collapse alone or around the scan as well. -- Kiryl Shutsemau / Kirill A. Shutemov