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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Zach O'Keefe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Branden Moore Subject: Re: [PATCH 1/2] mm/khugepaged: do synchronous writeback for MADV_COLLAPSE Message-ID: References: <20251110113254.77822-1-shivankg@amd.com> <39c8a4ed-53b5-48e3-baea-f67cc1e8be4f@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <39c8a4ed-53b5-48e3-baea-f67cc1e8be4f@amd.com> X-Stat-Signature: cnk36co1hxpy4fa73qz4554aomsokah9 X-Rspam-User: X-Rspamd-Queue-Id: D5BE3C000A X-Rspamd-Server: rspam10 X-HE-Tag: 1762784944-557710 X-HE-Meta: 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 hOJyi8Q9 97DkD3GWY1KoqMwn6Zzvs+iMiJrD9+wjhWqAAACtqW+19XxYhzoyQWKfPNCgKryZpu69K0ui9HrS2tqynQ263qkLbOrGPSRHt6zC0BgY7UqBarxWKoSxgCjoC1ZS5kEFhOghoGDPfFGigaIhrOfZKHm5HkOp7fZR3XO8hE+WApvHve3beGc5P67mBnLcqhD8cQ68iP/1op86DuCZJtikr1XK9X1aU91LIQcxDyXEIwd4BoYwWKCvq5h4JmMZXHyDY2QwyyCSPnwWa5pBW+SAvGJMi8xBlKbqZjjDxXGi7471QnlY= 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, Nov 10, 2025 at 07:50:17PM +0530, Garg, Shivank wrote: > The issue is copying those binary to a freshly mounted filesystem. > The page cache folios remain dirty until background writeback completes. > > Reproduces 100% for me: fresh XFS/EXT4 mount -> copy binary -> execute -> MADV_COLLAPSE fails. Yes, but this is an uncommon thing to do. Really, it's the kind of thing you do when you're testing something (like, whether ext4 supports large folios, and whether that yields a performance improvement). It's more reasonable to change userspace than the kernel to solve this problem you're having.