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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 14B24C7EE22 for ; Wed, 10 May 2023 06:08:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1F12D6B0071; Wed, 10 May 2023 02:08:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A1C76B0072; Wed, 10 May 2023 02:08:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 069CE6B0074; Wed, 10 May 2023 02:08:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id EAE1F6B0071 for ; Wed, 10 May 2023 02:08:50 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id A7ABC160554 for ; Wed, 10 May 2023 06:08:50 +0000 (UTC) X-FDA: 80773316820.07.3343910 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf08.hostedemail.com (Postfix) with ESMTP id 6439A160011 for ; Wed, 10 May 2023 06:08:47 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=GqtBVAri; spf=none (imf08.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1683698928; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=/B3tOo2DcdV+TWomt1rdQnWS8nj/GpV0fFl476JBaqo=; b=kH6MmhvPATHPDIrhTWlY2p3KUTQiredgQYwnOJXf2FL4R5ABOvd/jQl0eTLIM2LJW+5Vye yr3AZKsajmmYEngQTEMIISC6QfFdao/fxnorciQQ7thar4ylLN4YU/lyb0UuMNKwNiC3q+ Q1YTA54ZY62z7qUyq2md+cEt4vfOwUA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1683698928; a=rsa-sha256; cv=none; b=Nw00JIlT1KnBLOf2dFzo2H5jqbZPW8erRfJNOtIWATgWlsW9uQFa6JPL664qGImcIioPNi xY1PSkpGHzXOPz5w8MulL5re5END9SPwJmylYuSpBA447qj7U/bPS21DioJIj9Re5DQ18s NsbJ5AJmeD1+5AyGm5/1v3eccRDiVuU= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=GqtBVAri; spf=none (imf08.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none 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=/B3tOo2DcdV+TWomt1rdQnWS8nj/GpV0fFl476JBaqo=; b=GqtBVAriUhmAJ9gyQunowN/4FI IKPnDz7LbDDzd0Fgb9Z22xH9B0GothgTazfupCK9odsy8jdQ7d5rjIU0buEMmJgHPsqbRmD3rjRlS pe9WkgZOQJjVVUr2Nn9sQ+jGwW9hZdqgIKJXJ8Sf5r1YY8KiJJck+y51d1I4lWN/uji1Mhux3PR9z 4FQGYDQlCPyDgWt1HB2pIN4QBP8zK1HHd8c8SPjYOnj4IT/rnTHO2Gch9hA825q32K7voVZkZwShj 4YKfoYDVbZy6WQjNBqGFIRoL8UF3dgWpYlgtRh3uLSK2Af3sbYZbz1g5vy/PAMZKbCX9yrTkl5Mjy NzylU7Eg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pwcyp-00FzBu-D0; Wed, 10 May 2023 06:07:15 +0000 Date: Wed, 10 May 2023 07:07:15 +0100 From: Matthew Wilcox To: Hugh Dickins Cc: Andrew Morton , Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Russell King , Catalin Marinas , Will Deacon , Geert Uytterhoeven , Greg Ungerer , Michal Simek , Thomas Bogendoerfer , Helge Deller , John David Anglin , "Aneesh Kumar K.V" , Michael Ellerman , Alexandre Ghiti , Palmer Dabbelt , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda , John Paul Adrian Glaubitz , "David S. Miller" , Chris Zankel , Max Filippov , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 00/23] arch: allow pte_offset_map[_lock]() to fail Message-ID: References: <77a5d8c-406b-7068-4f17-23b7ac53bc83@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <77a5d8c-406b-7068-4f17-23b7ac53bc83@google.com> X-Rspamd-Queue-Id: 6439A160011 X-Stat-Signature: wqujseq1ou8bciicnuggf7fpyaojus7z X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1683698927-995401 X-HE-Meta: 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 OGqhrdIz TRcSz72Z7FTmznwrnovKCmE4LDDRlIAY1DfEVJQO3QU+12kTLyhJlv9qmIWEg8coAll9Vpkaj+KYEB/cfeVY/3YE6yHZnPvQpCUYWiDN2lZUIvirffDHYqIdJs17oQ1aEyCLojgCSWLj+Iji+RSQD5rb62x+pmxJEhqbbSymsLKlGGEJ9FlxcwvrxOA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, May 09, 2023 at 09:39:13PM -0700, Hugh Dickins wrote: > Two: pte_offset_map() will need to do an rcu_read_lock(), with the > corresponding rcu_read_unlock() in pte_unmap(). But most architectures > never supported CONFIG_HIGHPTE, so some don't always call pte_unmap() > after pte_offset_map(), or have used userspace pte_offset_map() where > pte_offset_kernel() is more correct. No problem in the current tree, > but a problem once an rcu_read_unlock() will be needed to keep balance. Hi Hugh, I shall have to spend some time looking at these patches, but at LSFMM just a few hours ago, I proposed and nobody objected to removing CONFIG_HIGHPTE. I don't intend to take action on that consensus immediately, so I can certainly wait until your patches are applied, but if this information simplifies what you're doing, feel free to act on it.