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Sun, 30 Aug 2026 08:23:13 -0700 (PDT) Date: Sun, 30 Aug 2026 23:23:03 +0800 From: Kairui Song To: "David Hildenbrand (Arm)" Cc: kasong@tencent.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C2B9D10000C X-Stat-Signature: 9ngch7r4u9e7t6yfc3j7wcyt6jbs45cd X-HE-Tag: 1788103395-229350 X-HE-Meta: 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 sqvAOqL8 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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.