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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Wilcox , Bas van Dijk , Eero Kelly , Andrew Battat , Adam Bratschi-Kaye , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3] selftests/mm: add folio_split() and filemap_get_entry() race test Message-Id: <20260319194118.3eb42ee3c507fd0ce2cd66bd@linux-foundation.org> In-Reply-To: <20260319190409.294523-1-ziy@nvidia.com> References: <20260319190409.294523-1-ziy@nvidia.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: bfiasw8gqj9yfasmsz9hr67486bz9s4j X-Rspam-User: X-Rspamd-Queue-Id: E0749140002 X-Rspamd-Server: rspam12 X-HE-Tag: 1773974480-341221 X-HE-Meta: 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 1wh/2QQw bnEIe5LTBqMoC6wkKrQ9TGI8SaAuspAaW5o6BUMFKsg+9LINpiI28oSJiOrQ7q4reLw/Kp8HQwAw72X7gK4ucj3nMbaU4w5xNsq4KzfB6LT7opupok+xJLXO/jP8e41YNcBte8M3n2BWojMu2dytn4eI0xIVZhz9zYRB8gbMkLZCicxmbIdouK6XViHZx0EZK1NS6QGmsYlyaAS2eTHIT5/GtVsDRwHMoOQd91Njd5x2+Q/VomW0PReGdXM9WJSJLTT5WYGX5xNuZhZLtF+xMe9HyCtTCWLykv3IH/CakHoTHGjsMR5gayMnCm3dt2lCuF25u+9IhJN0W8T2yf+zX/IYyvFWG/VPRrxjTA391L6S0bcQFpaoxfS1LMJ2zPMJy0dhk Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 19 Mar 2026 15:04:08 -0400 Zi Yan wrote: > The added folio_split_race_test is a modified C port of the race condition > test from [1]. The test creates shmem huge pages, where the main thread > punches holes in the shmem to cause folio_split() in the kernel and > a set of 16 threads reads the shmem to cause filemap_get_entry() in the > kernel. filemap_get_entry() reads the folio and xarray split by > folio_split() locklessly. The original test[2] is written in rust and uses > memfd (shmem backed). This C port uses shmem directly and use a single > process. > > Note: the initial rust to C conversion is done by Cursor. Sashiko has questions: https://sashiko.dev/#/patchset/20260319190409.294523-1-ziy%40nvidia.com (this is getting painful :(. I hope they're worthwhile)