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(p200300d82f300b00cea90deed607041d.dip0.t-ipconnect.de. [2003:d8:2f30:b00:cea9:dee:d607:41d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42b316775f2sm12777750f8f.16.2025.11.10.06.54.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Nov 2025 06:54:56 -0800 (PST) Message-ID: <69884a4d-60cb-4a66-a225-38d3a17712c6@gmail.com> Date: Mon, 10 Nov 2025 15:54:55 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] mm/khugepaged: do synchronous writeback for MADV_COLLAPSE To: Lorenzo Stoakes , Matthew Wilcox Cc: Shivank Garg , Andrew Morton , Zi Yan , Baolin Wang , "Liam R . 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 References: <20251110113254.77822-1-shivankg@amd.com> <9b622374-778a-4459-aca9-4eb406a58516@gmail.com> <2e6153c9-1729-463a-86b5-0973b3f56ea6@lucifer.local> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <2e6153c9-1729-463a-86b5-0973b3f56ea6@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10.11.25 15:05, Lorenzo Stoakes wrote: > On Mon, Nov 10, 2025 at 02:03:43PM +0000, Matthew Wilcox wrote: >> On Mon, Nov 10, 2025 at 03:00:32PM +0100, David Hildenbrand (Red Hat) wrote: >>> On 10.11.25 14:47, Matthew Wilcox wrote: >>>> On Mon, Nov 10, 2025 at 11:32:53AM +0000, Shivank Garg wrote: >>>>> When MADV_COLLAPSE is called on file-backed mappings (e.g., executable >>>>> text sections), the pages may still be dirty from recent writes. The >>>> >>>> That explanation derails my brain entirely. Text isn't writable! How >>>> can the pages be dirty and file-backed text? >>> >>> Files are writable :) >> >> Well, if you're root ... >> >> -rwxr-xr-x 1 root root 158632 Jun 4 11:14 /bin/ls >> > > gcc foo.c -o foo && ./foo > > Is more the issue I think Yeah, that's my understanding as well. I guess stuff like package/container updates might similarly trigger it.