From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 04E37332917 for ; Thu, 30 Jul 2026 12:47:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785415679; cv=none; b=uNEKukoz8jS59my4r678TTXpZnsTzHmYrPeH6RPg9u7WFMl0jTX6/9tjKKZ+JGEQd0hJzmY1dHfMWahhfD1N+seW/LzEqG89jTGgkmi1VzjY5RbYGld27k1qGGVpuCfCwDKtKN0YZiDM6NnrJ6RUxvKV4OnnvUtFUmLKcK3bVPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785415679; c=relaxed/simple; bh=vGNxZzU5kdBQQY8oqsCMqklMvnWF6dELO9cerhvUBSM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OIDyD85sVS9CF4M88p5xQa7eiIeawE7zuhS1zIYG+y6Nwxu5MYpoBAODOT7OnB7QFvy8rrgkaRxhmNtvgZTBsvrelRFKhvKxOVKnsAN3Z6zsiDCaikfz/gMWF0Gn3seeoBys/6FZX+ei7jvjhzO055SlTQJZUVUirUxDqTn5pMM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=o09DWJ22; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="o09DWJ22" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C3CE1F000E9; Thu, 30 Jul 2026 12:47:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785415677; bh=j9YnKQEuNyY3l6FqCLIt8DO3maEUsuk3WKolE6H8NO8=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=o09DWJ22Hv5sHflnQ1KniaNaofyCHe2ZxHKC48xizG9lN7TljgWIskyagAIXb1Bfl YC9oZaXML51B5Vh19zrnY46RxqekLzZB4LTnj6+19iR+CcSZYvaN6l0MYN5QrMBoL0 Tsynq4042P+2BCJphiI9H6z36IdoXTreK7b2+694Yoy0yC5oG/THF7LA2lHYPZijgK NtH7OX5WqDi9hbgbxupM4wvzpFZ8o9Ke7Re+gD+O0FPj8ur9kU52Ea+s0kVMDYxBX7 IlXGBs6CPlA8n3BoN/PgXPP0cz7aR9WQH1WlF/ZgNei3MFZE6v5c3FOlvWQlbvfz2J /x/efvJVmWLpQ== Message-ID: <86119f7f-bd70-428e-a6e0-eea7cc907bbe@kernel.org> Date: Thu, 30 Jul 2026 14:47:52 +0200 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 v4] mm/migrate_device: Clear stale mapping after freeing swapcache To: "Yadav, Arvind" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, ziy@nvidia.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, balbirs@nvidia.com References: <20260728062832.1107127-1-arvind.yadav@intel.com> <8d50f94b-6d95-4967-aa1f-2c14333ffd85@kernel.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 >> While this looks good, I do wonder why do we have to supply the mapping here >> at all? >> >> Is there a path where we call folio_migrate_mapping() and the old folio (folio) >> does no longer have the right mapping attached? >> >> It would be a lot less error prone if the function would just obtain the mapping >> from the old folio. > > > Agreed. I will make folio_migrate_mapping() obtain the mapping from the source > folio and update its in-tree callers. Since this changes an exported helper, I > will send it as a separate patch in v5. I think it would be good to understand why we currently pass in the folio: was there ever a reason to do so? Or why do we pass in something that can just easily be had from the source folio? But note that that should be a follow-up cleanup to the fix. -- Cheers, David