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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=B4kVC4DG; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81433606A32C; Mon, 26 Oct 2026 09:41:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=B4kVC4DG Received: by smtp.kernel.org (Postfix) with ESMTPSA id D55651F01825; Mon, 26 Oct 2026 09:41:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793007669; bh=+02ILXuK9KfO91BQX+g4W7G7YIbtI1+HIEbgN+bzPNs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=B4kVC4DGdBI0nHvQd38JB3xiE9r0i4N3qGwuJUEdjHaOsRrrDZWTPYEJgHeU9YP9E x5UEkksaPWu3fLn9gKPRdq9+DlZLl0tmGoNyWUTZOpghl1JA3iJtkPbRWENoHMLND0 8xydXSGcQL+2c4pEPRs5A5JdLRoUtySK0dNJxK8+ahLXPcv+8QCPc5omQkBWFUtcxY vA7PKr/GgjLz8qst218EKOSDbH04nxpTs0Dx06ndguB6lpIkRNDlWswaSwXP9c+WET C/MpOG0Myr+GqyGXVQ3kAUP5tjXu3f0N0sDBYOpKbf1s3bAHMKbcHbpeeWxIZKOy/I oC0Y/U9Fj1mgA== Message-ID: Date: Sun, 25 Oct 2026 13:36:12 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/ksm: keep soft-dirty when merging a page To: Andrew Morton , Samarth Narang Cc: Xu Xin , Chengming Zhou , Peter Xu , Kiryl Shutsemau , Mike Rapoport , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261021182157.1873726-1-samarth.colleges@gmail.com> <20261023223352.c6de9f2b58fe999814e5bb17@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/24/26 07:33, Andrew Morton wrote: > On Wed, 21 Oct 2026 11:21:57 -0700 Samarth Narang wrote: > >> replace_page() maps the KSM page with a PTE built from scratch, so the >> soft-dirty bit of the PTE it replaces is lost. A page written since >> "clear_refs 4" then no longer shows as soft-dirty once it is merged, and >> a soft-dirty based dumper treats it as unchanged. >> >> Copy the soft-dirty bit from the original PTE to the new PTE. > > Thanks. My LLM review thing says: > > : There's a separate, pre-existing problem with the KSM zero-page > : path which is worth pointing out. Cool, more AI schlop. TL;dr Sashiko raised this before and I commented why we don't care IIRC. -- Cheers, David