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[80.230.48.7]) by smtp.gmail.com with ESMTPSA id af79cd13be357-907b8e9b24asm1430902685a.18.2026.05.12.09.35.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2026 09:35:13 -0700 (PDT) Date: Tue, 12 May 2026 12:35:04 -0400 From: "Michael S. Tsirkin" To: Gregory Price 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 14/30] mm: hugetlb: use __GFP_ZERO and skip zeroing for zeroed pages Message-ID: <20260512123246-mutt-send-email-mst@kernel.org> References: <20260511174337-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: tDezF3NwRfSHnqs4vOgFQMr-iG-30fZZnQDOFphIhkc_1778603716 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: D0349140017 X-Stat-Signature: 486nj16j3i5kjf7arimtby46otpddr3u X-Rspam-User: X-HE-Tag: 1778603719-881454 X-HE-Meta: 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 LIsF3BVF 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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 Mon, May 11, 2026 at 10:49:06PM -0400, Gregory Price wrote: > On Mon, May 11, 2026 at 05:47:48PM -0400, Michael S. Tsirkin wrote: > > On Mon, May 11, 2026 at 12:36:59PM -0400, Gregory Price wrote: > > > > > > This feels like a very odd pattern: > > > > > > 1) ask for __GFP_ZERO > > > 2) Have to check whether it was actually zeroed > > > > > > Seems like the zeroing piece should just be sunk in if you're going to > > > ask for __GFP_ZERO anyway. And in that case, maybe just `bool zero` as > > > an argument, rather than GFP (to avoid future overloading of flags). > > > > > > ~Gregory > > > > Heh. The reason is that it either allocates from buddy - using gfp flags > > or from the pool, in which case it zeroes. > > > > We could even avoid the bool - just test __GFP_ZERO inside > > alloc_hugetlb_folio. Would that be better? > > > > Hard to know until we see the full shape of things, but it seems > reasonable if we can eliminate one or both new arguments that this would > be a good thing and the logic should just be sunk into hugetlb. > > ~Gregory BTW it does mean we need to use vmf->real_address there as user_addr as opposed to vmf->address which is HP aligned. I guess I'll switch everyone to use real_address then, for consistency. -- MST