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[100.36.248.188]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8fc2c9229c8sm3399020585a.36.2026.05.11.09.39.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 May 2026 09:39:20 -0700 (PDT) Date: Mon, 11 May 2026 12:39:18 -0400 From: Gregory Price To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, "David Hildenbrand (Arm)" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Muchun Song , Oscar Salvador , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Hugh Dickins , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Axel Rasmussen , Yuanchu Xie , Wei Xu , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , virtualization@lists.linux.dev, linux-mm@kvack.org, Andrea Arcangeli Subject: Re: [PATCH resend v6 15/30] mm: memfd: skip zeroing for zeroed hugetlb pool pages Message-ID: References: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, May 11, 2026 at 05:03:08AM -0400, Michael S. Tsirkin wrote: > gather_surplus_pages() pre-allocates hugetlb pages into the pool > during mmap. Pass __GFP_ZERO so these pages are zeroed by the > buddy allocator, and HPG_zeroed is set by alloc_surplus_hugetlb_folio. > > Add bool *zeroed output to alloc_hugetlb_folio_reserve() so > callers can check whether the pool page is known-zero. memfd's > memfd_alloc_folio() uses this to skip the explicit folio_zero_user() > when the page is already zero. > > This avoids redundant zeroing for memfd hugetlb pages that were > pre-allocated into the pool and never mapped to userspace. > Same thing here, seems more like what's actually wanted is to sink the folio_user_zero stuff into hugetlb.c rather than make memfd.c request for zeroing - and then have to check again anyway. ~Gregory