From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1FFD1E25F9; Mon, 10 Nov 2025 14:03:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762783439; cv=none; b=jRPrN+AcMgmXOrMNp8vQzcwZcsDUllfAst/LYQHv4WqrleIMqKG6KjDcejn37Espd/IkIxurEqrEDT4pAsu3bI5SEmXG6KeLJuIvvtVnDkv0DhC9OSYCcVtzL6rGS0xJF1IyYysPwOUqP77VdNCqvgvQfYxHkyNppBBRVbKjVTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762783439; c=relaxed/simple; bh=/Y98uMcnJToTBczwgLqc2/K1GX9+g9UTB5e0jGzo9q8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QnkRYzbjKvTdENWvmjYffkgoZU/cXp2Qng76ucg24zK5K4T9wJFU7vZfgdtmTICRLfA/iXQGLwD3adiC9uGCVKlQfaEHkkxx+RuhgRDWPsgFc3G0HLgUEPaJXE84SY+YOVdxdvc2bRvfsWrzU4PhYFx+DVQVPNCK/NSG+Mtp3RQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=APBOPyKN; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="APBOPyKN" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=wTntukXdaVFjnftz5WTTeF+x0iVhUlIwTUQPH67TnYI=; b=APBOPyKNe6JNBjwvNL5ANy0RHS 6FNALoWP8USB0oxkWef8vyXGcUJ8QSiW6uIkCWiB/EIfRyqrImuDNRpbA9wWzVBdmn68foHJ1kDIh JLGqmtmQNQJEA9SXC9s2V5O14WEQyyPZaE19sGkWZYxsTx1WR5ZLU07/9gMwST/Zlo87g67UQMqQA HpbrFRnKHlhUxREbF+vv5DVk/ZNxmOF4QMCzG7IYGXk7CX/SZRGXr9miHifFgv2Gxkdf/JW7juAZk /reX6S9bZHznt9sJo3+2btv63m8oA7k86Bqwlg0JYGbVworWUEN3A3Nd0KlZLMiFOmTG5Wl+yIZoy tUGoVX8w==; Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vISUh-0000000GkmP-35kQ; Mon, 10 Nov 2025 14:03:43 +0000 Date: Mon, 10 Nov 2025 14:03:43 +0000 From: Matthew Wilcox To: "David Hildenbrand (Red Hat)" Cc: Shivank Garg , Andrew Morton , Lorenzo Stoakes , 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 Subject: Re: [PATCH 1/2] mm/khugepaged: do synchronous writeback for MADV_COLLAPSE Message-ID: References: <20251110113254.77822-1-shivankg@amd.com> <9b622374-778a-4459-aca9-4eb406a58516@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9b622374-778a-4459-aca9-4eb406a58516@gmail.com> 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