From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9791C28D13 for ; Mon, 22 Aug 2022 19:54:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233729AbiHVTy0 (ORCPT ); Mon, 22 Aug 2022 15:54:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231326AbiHVTyZ (ORCPT ); Mon, 22 Aug 2022 15:54:25 -0400 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 39864402FD for ; Mon, 22 Aug 2022 12:54:24 -0700 (PDT) Received: by mail-lf1-x136.google.com with SMTP id a16so8467130lfs.3 for ; Mon, 22 Aug 2022 12:54:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc; bh=mJYkjoFM1MNYDjxafvXKEPUbvJhzVrTSHnNsQsuncUA=; b=AsCF/DmtHu2Jmnl9CHMjfwMS+IXEr7nmauJCOI8GcgiO7HgXBdj+UWyVv11d5fVSs6 LDPpik1XpQcnxNI5k/evDP8Kb9U3Te5Qjplyi8TAS2F4H57aZRz/3oKx7Iv8ezdzImyZ oytbi1mUJ76xXIBiWcTM7EmbGckM8K5mj5+F9BtK7sqrWZ4z/eM1Wg4l/V9iuDSAaqRN FDi4uJ0rOrQrVshXWq5YExAMlKOk13pNorYc0qn78gM8cJwx8WBnEvIpeaZ4IUIxBdY7 inaJsAZ9fhFf7bWULI/1R2cWSS5wxOwgb5w51gD9Dh5NvrD78ZjQ0Z8tumtMVoiGf5/3 PetA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc; bh=mJYkjoFM1MNYDjxafvXKEPUbvJhzVrTSHnNsQsuncUA=; b=6cVCwm8jTxzDwYL7yeOncXpiVynJTiDf3iFOcpsT5HCburAYH58j+16j2yOOQosBKP o+IXGqUs3ZXA3qNoC39YfSilAowgRF7u5hQBcn/oBlHcKiV3B6pueKp+AG0qAlhdkXkw UgRNZfCq+nnQB4a30O4bwFnqFivRsk8QoJn3ueY4XEuN6PCSolGZ35f96KWqHn+8OBNt ahDpvsqpsx8gvCasVpr4opHgfP0PJdPSJgrjwtX3qUrLUwRvYI8ERCBrezpIXY/PgHyn /hnPAyXK1FnnpOnY2tRuPGjGF7KTpMLIPklmW5v8X07MRYORqz7i0Fos7ea2RQIkNSCR 5Nvw== X-Gm-Message-State: ACgBeo3qQ189JVLmS5aIMRfqf9NnamKQBxttiiLVqTUXv0boa2+uvvdu DbIT7wUaYPxRSnJAoa02BEk= X-Google-Smtp-Source: AA6agR4gMsy8l1NhQm/H2kJ/k9mi/lPb1q9eNX5xzbOH/YfWEJirzsqfcrr4tJ2FzPRiVne+Rm4agw== X-Received: by 2002:a05:6512:acd:b0:492:b8e0:2ef4 with SMTP id n13-20020a0565120acd00b00492b8e02ef4mr6981068lfu.360.1661198062396; Mon, 22 Aug 2022 12:54:22 -0700 (PDT) Received: from pc636 ([155.137.26.201]) by smtp.gmail.com with ESMTPSA id p5-20020a05651238c500b0048a83336343sm2075680lft.252.2022.08.22.12.54.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Aug 2022 12:54:21 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 22 Aug 2022 21:54:17 +0200 To: Matthew Wilcox Cc: Uladzislau Rezki , Thomas Gleixner , Ira Weiny , "Fabio M. De Francesco" , Luis Chamberlain , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC] vmap_folio() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Aug 19, 2022 at 04:45:05PM +0100, Matthew Wilcox wrote: > On Fri, Aug 19, 2022 at 12:53:32PM +0200, Uladzislau Rezki wrote: > > Looks pretty straightforward. One thing though, if we can combine it > > together with vmap(), since it is a copy paste in some sense, say to > > have something __vmap() to reuse it in the vmap_folio() and vmap(). > > > > But that is just a thought. > > Thanks for looking it over! > You are welcome. > > Combining it with vmap() or vm_map_ram() is tricky. Today, we assume > that each struct page pointer refers to exactly PAGE_SIZE bytes, so if > somebody calls alloc_pages(GFP_COMPOUND, 4) and then passes the head > page to vmap(), only that one page gets mapped. I don't know whether > any current callers depend on that behaviour. > > Now that I look at the future customers of this, I think I erred in basing > this on vmap(), it looks like vm_map_ram() is preferred. So I'll redo > based on vm_map_ram(). > Indeed, the vmap code has no knowledge about comound pages. You can add me to CC, so i can have a look on it to help out with it if there will be a need. -- Uladzislau Rezki