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Tue, 21 Oct 2025 02:17:13 -0400 (EDT) Date: Tue, 21 Oct 2025 07:17:11 +0100 From: Kiryl Shutsemau To: Christoph Hellwig Cc: Dave Chinner , Andrew Morton , David Hildenbrand , Hugh Dickins , Matthew Wilcox , Alexander Viro , Christian Brauner , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Rik van Riel , Harry Yoo , Johannes Weiner , Shakeel Butt , Baolin Wang , "Darrick J. Wong" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC, PATCH 0/2] Large folios vs. SIGBUS semantics Message-ID: References: <20251020163054.1063646-1-kirill@shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 1A999140007 X-Stat-Signature: ahsq1iforyh4bdopmkc13kqrfsyf3941 X-Rspam-User: X-HE-Tag: 1761027436-929442 X-HE-Meta: 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 q5QE5Hhb e5ib3OIxLvocfvbIZ/O237M/h/e33r1fvk48MggrNX5Zt2kQmph5qIGwDCGnnOK5PkmDu06iFtBHLvvNsTjzHnH0oLE9LesXSgJD+GvHsJuXf/0FigWpM9FoF/fQ/Y4dSqm6VxMUT8N0weLRUbdNiFaLWWEAE/qCkmMe5cNHhTbu8/IcsyON0Eeud/wbxMQLxQvRDBOBqZyIjtnqmru4jPYD0DM6bqOU9SDak3/85dBS1ysiRI4y+7D5zh7CyjBq8C4slo1N7COI10ZQ4sVUeaMs5CUoR7owUvZ8c+EMrWMqfBTWwlq9S20OfotGPv0Nj3etNGvTAjb8T2vP8lqmMo8saZNgedrBgG+3kzFG810XgMRKGwvF2P0sw0RYeoGimoE1EZ/X67iXZlUrlmPMfnRiVComFn7mqZN7XXqiYCFOBShiv5mdXDZ/DDqhGVBo6n9om X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Oct 20, 2025 at 11:12:40PM -0700, Christoph Hellwig wrote: > On Tue, Oct 21, 2025 at 10:28:02AM +1100, Dave Chinner wrote: > > Fundamentally, we really don't care about the mapping/tlb > > performance of the PTE fragments at EOF. Anyone using files large > > enough to notice the TLB overhead improvements from mapping large > > folios is not going to notice that the EOF mapping has a slightly > > higher TLB miss overhead than everywhere else in the file. > > > > Please jsut fix the regression. > > Yeah. I'm not even sure why we're having this discussion. The > behavior is mandated, we have test cases for it and there is > literally no practical upside in changing the behavior from what > we've done forever and what is mandated in Posix. Okay, will fix. -- Kiryl Shutsemau / Kirill A. Shutemov