From patchwork Wed Sep 18 13:19:11 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jia He X-Patchwork-Id: 11150355 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D762413BD for ; Wed, 18 Sep 2019 13:19:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ACE202067B for ; Wed, 18 Sep 2019 13:19:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ACE202067B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DDE8E6B02B0; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id D8F636B02B2; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7E5B6B02B3; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id A5D9D6B02B0 for ; Wed, 18 Sep 2019 09:19:31 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 0FA46180AD802 for ; Wed, 18 Sep 2019 13:19:31 +0000 (UTC) X-FDA: 75948098142.14.bomb29_701056495ee18 X-Spam-Summary: 2,0,0,e8eead63fe6a808c,d41d8cd98f00b204,justin.he@arm.com,:catalin.marinas@arm.com:will@kernel.org:mark.rutland@arm.com:james.morse@arm.com:maz@kernel.org:willy@infradead.org:kirill.shutemov@linux.intel.com:linux-arm-kernel@lists.infradead.org:linux-kernel@vger.kernel.org::suzuki.poulose@arm.com:punitagrawal@gmail.com:anshuman.khandual@arm.com:yaojun8558363@gmail.com:avanbrunt@nvidia.com:robin.murphy@arm.com:tglx@linutronix.de:akpm@linux-foundation.org:jglisse@redhat.com:rcampbell@nvidia.com:hejianet@gmail.com:kaly.xin@arm.com:justin.he@arm.com,RULES_HIT:41:355:379:541:968:988:989:1260:1261:1345:1437:1534:1541:1711:1730:1747:1777:1792:1801:2393:2559:2562:2693:2901:3138:3139:3140:3141:3142:3352:3865:3866:3868:3870:3871:4605:5007:6117:6119:6261:6737:6742:7903:8634:10004:11026:11473:11658:11914:12043:12048:12291:12296:12297:12438:12679:12895:13069:13311:13357:14096:14384:14394:14581:14721:21080:21451:21627:21795:30051:30054:30070:30090,0,RBL:217.140.110.172:@arm. com:.lbl X-HE-Tag: bomb29_701056495ee18 X-Filterd-Recvd-Size: 2861 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Sep 2019 13:19:29 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 043BE1000; Wed, 18 Sep 2019 06:19:29 -0700 (PDT) Received: from localhost.localdomain (entos-thunderx2-02.shanghai.arm.com [10.169.40.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A36493F575; Wed, 18 Sep 2019 06:19:23 -0700 (PDT) From: Jia He To: Catalin Marinas , Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose Cc: Punit Agrawal , Anshuman Khandual , Jun Yao , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , Ralph Campbell , hejianet@gmail.com, Kaly Xin , Jia He Subject: [PATCH v4 0/3] fix double page fault on arm64 Date: Wed, 18 Sep 2019 21:19:11 +0800 Message-Id: <20190918131914.38081-1-justin.he@arm.com> X-Mailer: git-send-email 2.17.1 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: When we tested pmdk unit test vmmalloc_fork TEST1 in arm64 guest, there will be a double page fault in __copy_from_user_inatomic of cow_user_page. As told by Catalin: "On arm64 without hardware Access Flag, copying from user will fail because the pte is old and cannot be marked young. So we always end up with zeroed page after fork() + CoW for pfn mappings. we don't always have a hardware-managed access flag on arm64." Changes v4: introduce cpu_has_hw_af (Suzuki) bail out if !pte_same (Kirill) v3: add vmf->ptl lock/unlock (by Kirill A. Shutemov) add arch_faults_on_old_pte (Matthew, Catalin) v2: remove FAULT_FLAG_WRITE when setting pte access flag (by Catalin) Jia He (3): arm64: cpufeature: introduce helper cpu_has_hw_af() arm64: mm: implement arch_faults_on_old_pte() on arm64 mm: fix double page fault on arm64 if PTE_AF is cleared arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/include/asm/pgtable.h | 12 ++++++++++ arch/arm64/kernel/cpufeature.c | 6 +++++ mm/memory.c | 35 ++++++++++++++++++++++++----- 4 files changed, 49 insertions(+), 5 deletions(-)