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[80.230.48.7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-454913049ecsm32654384f8f.19.2026.05.12.08.46.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 May 2026 08:46:51 -0700 (PDT) Date: Tue, 12 May 2026 11:46:46 -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 17/30] mm: page_alloc: propagate PageReported flag across buddy splits Message-ID: <20260512114352-mutt-send-email-mst@kernel.org> References: <6d98a35c94fa44b550afa66923c620511e2826f0.1778489843.git.mst@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: zCHVlZeImaumu-5Juf2nJcscN4s7eoaTuDc1dSmDw-U_1778600813 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Rspam-User: X-Rspamd-Queue-Id: 7D3ADC000A X-Rspamd-Server: rspam06 X-Stat-Signature: bd3fm5jr6f9r7x4qjr1paopwtakrau1y X-HE-Tag: 1778600818-255846 X-HE-Meta: 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 i0BOkbIw +P4a7uuhL9qJR06TeDNSEF9T5DH8Di893klgnz9UENKEEm/McIBcz8enbFmJhH7nxw5/YZlFVXlSx+914kZXmGIFrp8J1jg+spljxQwz8Pzu2GhPg3ohvu+aD1jelymYBiKTDJAOR+3z9rTD8zqJbkvlD/wp5LpkKVeg/wauz21a48F2LBDFPMDbkp3Nlg3BU1mpBGeTqnC7eIomph44qKT0d2VDdCKtK9E0NfseiAGd9JQnV+dn/65zCnk2WW+j42+ops38nzNLTmruvDMi2YieoSjEJgrjeFtwe84yY2ija3+HWh8LX2gWcVYpRlORdqpxLonIA9ECX7hyGPdiZuOlNchMWpXbPjcOfiwuo3NLc+CO30HeWQh7ShzQ0VFqken5P1xi4uHMM5DFA+wsBqX75Mw6mHUAoO6L5 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, May 12, 2026 at 11:40:08AM -0400, Gregory Price wrote: > On Mon, May 11, 2026 at 05:03:19AM -0400, Michael S. Tsirkin wrote: > > When a reported free page is split via expand() to satisfy a > > smaller allocation, the sub-pages placed back on the free lists > > lose the PageReported flag. This means they will be unnecessarily > > re-reported to the hypervisor in the next reporting cycle, wasting > > work. > > > > Is this issue generated by the changes in the overall patch set, or an > issue present regardless of the proposed zeroing avoidance feature? > > If the former, then maybe just submit as a standalone patch, seems like > a useful improvement regardless. The former but then the only issue is more reporting, and I couldn't find a benchmark that would quantify the performance difference. So the value of pushing a fix by itself is pretty low. > If fundamentally tied to the zeroing-avoidance feature, then nudging > this to the front or end of the series (depending on conflicts) would > help focus the review of the core new feature. > > ~Gregory I can nudge it forward sure. -- MST