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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , Shivam Kalra Subject: Re: [PATCH v3 09/18] mm/huge_memory: move anon_vma and filemap management into split helpers Message-ID: References: <20260821-swap-thp-cleanup-v3-0-9b43f5163238@tencent.com> <20260821-swap-thp-cleanup-v3-9-9b43f5163238@tencent.com> 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: On Thu, Aug 27, 2026 at 06:36:18PM +0800, David Hildenbrand (Arm) wrote: > On 8/20/26 20:55, Kairui Song via B4 Relay wrote: > > From: Kairui Song > > > > Only anon split needs vma info, and only file split needs the filemap > > handling. Move the related code into separate helpers so they are > > genuinely more self-contained. > > This patch seems to do more than that, like relocating the > folio_expected_ref_count check (and duplicating it, which is not so nice). We can keep it where it is right now, but this patch is moving the anon_vma_lock_write and i_mmap_lock_read into the two anon / file helpers seperately, so keeping the folio_expected_ref_count check outside and before the helper call will cause a potential higher false positive / negative rate of this check? Leads to unnecessary call to unmap_folio. How about moving the folio_expected_ref_count check into unmap_folio since the purpose of the ref check is to avoid unnecessary unmap? No more duplication that way.