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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9158a21f871sm1787135885a.12.2026.06.08.08.45.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 08:45:20 -0700 (PDT) Date: Mon, 8 Jun 2026 11:45:18 -0400 From: Gregory Price To: "Vlastimil Babka (SUSE)" Cc: "Michael S. Tsirkin" , 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" , 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 v10 00/37] mm/virtio: skip redundant zeroing of host-zeroed pages Message-ID: References: <8d5d2fa3-a60c-4d04-b3bf-7a8fe89cb1a0@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: On Mon, Jun 08, 2026 at 01:13:42PM +0200, Vlastimil Babka (SUSE) wrote: > On 6/8/26 13:02, Vlastimil Babka (SUSE) wrote: > > On 6/8/26 10:33, Michael S. Tsirkin wrote: > >> Further, on architectures with aliasing caches, upstream with init_on_alloc > > > > It seems those are niche architectures so we can ignore that part for perf > > purposes; the other reason why user_alloc_needs_zeroing() would be true is > > booting with init_on_alloc. > > OK I misread how user_alloc_needs_zeroing() works wrt init_on_alloc, as it's > negated. But you're changing that anyway to skip that user zeroing, right? > > " > This series eliminates that double-zeroing by moving the zeroing > into the post_alloc_hook + propagating the "host > already zeroed this page" information through the buddy allocator. > " > > So relying on "everything in buddy is zeroed" would still work I'd think. > This regresses for anything that previously didn't zero on free or alloc, which is most kernel allocations. I think the scope of this set has increased too much based on early feedback to fix the userland-initiated allocations piece along with the balloon/reporting/double-zero piece. That's making all of this difficult to continue following. ~Gregory