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Wed, 16 Sep 2026 10:47:39 -0400 (EDT) Date: Wed, 16 Sep 2026 15:47:38 +0100 From: Kiryl Shutsemau To: Usama Arif Cc: Andrew Morton , david@kernel.org, chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org, ying.huang@linux.alibaba.com, Baoquan He , willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, Nico Pache , "Liam R. Howlett" , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com Subject: Re: [RESEND v7 08/29] mm: recognize PMD swap entries in the softleaf layer Message-ID: References: <20260914122950.3283997-1-usama.arif@linux.dev> <20260914122950.3283997-9-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260914122950.3283997-9-usama.arif@linux.dev> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 8D59B120008 X-Stat-Signature: 1megbq9ufa7u7q7cazt59gynbb6mjjqm X-Rspam-User: X-HE-Tag: 1789570070-329071 X-HE-Meta: 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 Bi+urqK4 UlJ+Hn7b7R4odKutCtylEGjUv/tlUjZR3qN7DK5YDgQaLBvY2CkmHkzkRbNbuVCYs1zp02QoY02qoJBsZ36Y/qaMWy6CswDCpDNZKBTz4wn2n6XJQbwMn8q+nhjKVrwsK2xX6qXzxhlqqWK6Qvae7yWzpVaHh1jbiZJXCDZQqwCFU8uZTKKzO2dZcknSZobncIMnr6bTM3aW9Szj/tXnt9b/lXvt91cDNASgAivgUpdUzSdnbbysdktI3PsJIVHipjgrRAw13mOLlc1WNzhgcpXFhziFsKwUKYYK1QlspLPeMkDc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 14, 2026 at 05:27:58AM -0700, Usama Arif wrote: > Reclaim splits a PMD-mapped anonymous THP into PTE-level swap entries > before unmapping it, so an ordinary swap entry has never had to appear in a > PMD. Later patches install one there instead, and the softleaf layer is > where every consumer decodes non-present PMDs. > > Accept swap entries as valid PMD softleaves and add pmd_is_swap_entry(). > A swap entry carries no PFN, so make pmd_softleaf_to_folio() warn and > return NULL rather than interpret a swap offset as a page frame number. > > Unlike migration and device-private entries, a PMD swap entry can also > carry the swap-exclusive marker, which softleaf_from_pmd() has to strip > before decoding. Strip all three overlays unconditionally while we are > here: each clear is a plain bit clear, so testing first only buys a branch. > > Signed-off-by: Usama Arif Reviewed-by: Kiryl Shutsemau (Meta) -- Kiryl Shutsemau / Kirill A. Shutemov