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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-89c0dbcd225sm441582885a.12.2025.10.24.11.41.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Oct 2025 11:41:05 -0700 (PDT) Date: Fri, 24 Oct 2025 14:41:02 -0400 From: Gregory Price To: Lorenzo Stoakes Cc: Andrew Morton , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Chris Li , Peter Xu , Matthew Wilcox , Jason Gunthorpe , Leon Romanovsky , Muchun Song , Oscar Salvador , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Pedro Falcato , Pasha Tatashin , Rik van Riel , Harry Yoo , kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 09/12] mm/huge_memory: refactor change_huge_pmd() non-present logic Message-ID: References: <282c5f993e61ca57a764a84d0abb96e355dee852.1761288179.git.lorenzo.stoakes@oracle.com> Precedence: bulk X-Mailing-List: kvm@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: <282c5f993e61ca57a764a84d0abb96e355dee852.1761288179.git.lorenzo.stoakes@oracle.com> On Fri, Oct 24, 2025 at 08:41:25AM +0100, Lorenzo Stoakes wrote: > Similar to copy_huge_pmd(), there is a large mass of open-coded logic for > the CONFIG_ARCH_ENABLE_THP_MIGRATION non-present entry case that does not > use thp_migration_supported() consistently. > > Resolve this by separating out this logic and introduce > change_non_present_huge_pmd(). > > Signed-off-by: Lorenzo Stoakes > --- --- >8 > + if (thp_migration_supported() && is_swap_pmd(*pmd)) { > + change_non_present_huge_pmd(mm, addr, pmd, uffd_wp, > + uffd_wp_resolve); You point out the original code doesn't have thp_migration_supported() is this a bug? or is it benign and just leads to it failing (nicely) deeper in the stack? If it's a bug, maybe this patch should be pulled out ahead of the rest? ~Gregory