From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (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 67EA0345725 for ; Wed, 29 Jul 2026 17:33:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.67.55.147 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785346383; cv=none; b=rNQx4OG72VRJ7xSQnjFVT9v8JnF5zNQdED5izZOxqheW9QF59vuSuA/oQNlk0t2G86jFEiajZXc3w7QM/rvwHsmj3zAmlvUB8RkDp4GNFewmectsh5nvfBTv5+4BgZJMHA88g2PXez+U/CiA1xP3fMLkHfQhazMyK7Hr5CsxcT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785346383; c=relaxed/simple; bh=FKPkK/MixdvkENkNVD4h19x1Fm9Q2SRwB6zQVpOUnbc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=qvlogjnRTaS2/c27UZAzgxToD7zspmQReGN0GUNWZ4xqK2i6N8CDTFT+fEjzG4jliln4M+RNouhAM6ruEJK1EKvtIfJBHyjYStzkI6VxYUO7S4YuYFf9jUi/1iIDOz89Cjnk5It3Kcr2Ec8Dlu5D79/yTTv40hAqAZbLCDUDKbY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com; spf=pass smtp.mailfrom=surriel.com; dkim=pass (2048-bit key) header.d=surriel.com header.i=@surriel.com header.b=Im3l2SZG; arc=none smtp.client-ip=96.67.55.147 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=surriel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=surriel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=surriel.com header.i=@surriel.com header.b="Im3l2SZG" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=surriel.com ; s=mail; h=MIME-Version:Content-Transfer-Encoding:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=pEb8Bd5m5xa8tu6hvQqbyARRDUBCS3xJAvu2ciC4syI=; b=Im3l2SZGB5RJ2y1IabZ/DfirIB 4rjdzTIdhLZB0hdrG9+W/0+4ctuo+tTn8xqyMBNV/owAV/8tpZLlKs4moIu5Nraf/CYHrgLFctqkQ f/80vjwDUvZGNAUr3uDQo/9tFU7M28n1MgHpNohrhYvie1LsBOEQQAyrzLWlKhawbz4tbsOfjFKQ2 QPUXkPS3Tj0XuDbJeWJfx3YFbSo9QGWNEqRbvHedh/2IYex9MOtaz6z2FMYl6duv5OfDsDOHOuXs1 o8wpIyVN1GnRj1rdyIXtr09zDF2nfv9CHgimadmGYWtVX1eHNgTSILZTW5xrMlH3nYmxfnBjU4QgY g1RxJwyg==; Received: from fangorn.home.surriel.com ([10.0.13.7]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from ) id 1wp87q-000000006BO-1M8h; Wed, 29 Jul 2026 13:31:26 -0400 Message-ID: <432cbf0c1194174259736d929f7f919ef55d19a9.camel@surriel.com> Subject: Re: [PATCH 1/2] mm/gup: pass an end address to follow_page_mask() and return a page count From: Rik van Riel To: "David Hildenbrand (Arm)" , linux-kernel@vger.kernel.org Cc: Andrew Morton , linux-mm@kvack.org, Dave Hansen , Peter Zijlstra , Suren Baghdasaryan , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Mike Rapoport , Michal Hocko , Jason Gunthorpe , John Hubbard , Peter Xu , Matthew Wilcox , Usama Arif , kernel-team@meta.com Date: Wed, 29 Jul 2026 13:31:26 -0400 In-Reply-To: References: <20260729030234.2063885-1-riel@surriel.com> <20260729030234.2063885-2-riel@surriel.com> Autocrypt: addr=riel@surriel.com; prefer-encrypt=mutual; keydata=mQENBFIt3aUBCADCK0LicyCYyMa0E1lodCDUBf6G+6C5UXKG1jEYwQu49cc/gUBTTk33A eo2hjn4JinVaPF3zfZprnKMEGGv4dHvEOCPWiNhlz5RtqH3SKJllq2dpeMS9RqbMvDA36rlJIIo47 Z/nl6IA8MDhSqyqdnTY8z7LnQHqq16jAqwo7Ll9qALXz4yG1ZdSCmo80VPetBZZPw7WMjo+1hByv/ lvdFnLfiQ52tayuuC1r9x2qZ/SYWd2M4p/f5CLmvG9UcnkbYFsKWz8bwOBWKg1PQcaYHLx06sHGdY dIDaeVvkIfMFwAprSo5EFU+aes2VB2ZjugOTbkkW2aPSWTRsBhPHhV6dABEBAAG0HlJpayB2YW4gU mllbCA8cmllbEByZWRoYXQuY29tPokBHwQwAQIACQUCW5LcVgIdIAAKCRDOed6ShMTeg05SB/986o gEgdq4byrtaBQKFg5LWfd8e+h+QzLOg/T8mSS3dJzFXe5JBOfvYg7Bj47xXi9I5sM+I9Lu9+1XVb/ r2rGJrU1DwA09TnmyFtK76bgMF0sBEh1ECILYNQTEIemzNFwOWLZZlEhZFRJsZyX+mtEp/WQIygHV WjwuP69VJw+fPQvLOGn4j8W9QXuvhha7u1QJ7mYx4dLGHrZlHdwDsqpvWsW+3rsIqs1BBe5/Itz9o 6y9gLNtQzwmSDioV8KhF85VmYInslhv5tUtMEppfdTLyX4SUKh8ftNIVmH9mXyRCZclSoa6IMd635 Jq1Pj2/Lp64tOzSvN5Y9zaiCc5FucXtB9SaWsgdmFuIFJpZWwgPHJpZWxAc3VycmllbC5jb20+iQE +BBMBAgAoBQJSLd2lAhsjBQkSzAMABgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRDOed6ShMTe g4PpB/0ZivKYFt0LaB22ssWUrBoeNWCP1NY/lkq2QbPhR3agLB7ZXI97PF2z/5QD9Fuy/FD/jddPx KRTvFCtHcEzTOcFjBmf52uqgt3U40H9GM++0IM0yHusd9EzlaWsbp09vsAV2DwdqS69x9RPbvE/Ne fO5subhocH76okcF/aQiQ+oj2j6LJZGBJBVigOHg+4zyzdDgKM+jp0bvDI51KQ4XfxV593OhvkS3z 3FPx0CE7l62WhWrieHyBblqvkTYgJ6dq4bsYpqxxGJOkQ47WpEUx6onH+rImWmPJbSYGhwBzTo0Mm G1Nb1qGPG+mTrSmJjDRxrwf1zjmYqQreWVSFEt26tBpSaWsgdmFuIFJpZWwgPHJpZWxAZmIuY29tP okBPgQTAQIAKAUCW5LbiAIbIwUJEswDAAYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQznneko TE3oOUEQgAsrGxjTC1bGtZyuvyQPcXclap11Ogib6rQywGYu6/Mnkbd6hbyY3wpdyQii/cas2S44N cQj8HkGv91JLVE24/Wt0gITPCH3rLVJJDGQxprHTVDs1t1RAbsbp0XTksZPCNWDGYIBo2aHDwErhI omYQ0Xluo1WBtH/UmHgirHvclsou1Ks9jyTxiPyUKRfae7GNOFiX99+ZlB27P3t8CjtSO831Ij0Ip QrfooZ21YVlUKw0Wy6Ll8EyefyrEYSh8KTm8dQj4O7xxvdg865TLeLpho5PwDRF+/mR3qi8CdGbkE c4pYZQO8UDXUN4S+pe0aTeTqlYw8rRHWF9TnvtpcNzZw== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-2.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-07-29 at 09:16 +0200, David Hildenbrand (Arm) wrote: >=20 > This patch moves us closer towards the GUP-fast path, however, that > is about to > change: >=20 > =09 > https://lore.kernel.org/all/20260219050250.266876166@ruivo.org/ >=20 > With that in mind, I guess in the future we want to have: >=20 > static long follow_page_mask(struct vm_area_struct *vma, > unsigned long address, unsigned long end, > unsigned int flags, struct page **pages) >=20 > or even better, now that follow_page() no longer exists, in light of > gup_fast(): >=20 >=20 > static long gup_slow(struct vm_area_struct *vma, > unsigned long address, unsigned long end, > unsigned int flags, struct page **pages) >=20 > Returning the number of pinned pages. >=20 >=20 > In particular, such an interface would allows us to process multiple > ptes/pmds/... in one go, without having to restart the page table > walk all the > time for each non-batchable folio. >=20 Let me give that a try. This looks like a very nice optimization, and cleanup. --=20 All Rights Reversed.