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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1AB64C3A5A6 for ; Thu, 19 Sep 2019 16:42:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6A1620882 for ; Thu, 19 Sep 2019 16:42:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732777AbfISQmM (ORCPT ); Thu, 19 Sep 2019 12:42:12 -0400 Received: from foss.arm.com ([217.140.110.172]:33950 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732225AbfISQmL (ORCPT ); Thu, 19 Sep 2019 12:42:11 -0400 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 2FF0B28; Thu, 19 Sep 2019 09:42:11 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9A4983F575; Thu, 19 Sep 2019 09:42:08 -0700 (PDT) Date: Thu, 19 Sep 2019 17:42:06 +0100 From: Catalin Marinas To: Jia He Cc: 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 , Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?iso-8859-1?B?Suly9G1l?= Glisse , Ralph Campbell , hejianet@gmail.com, Kaly Xin Subject: Re: [PATCH v5 3/3] mm: fix double page fault on arm64 if PTE_AF is cleared Message-ID: <20190919164206.GE6472@arrakis.emea.arm.com> References: <20190919161204.142796-1-justin.he@arm.com> <20190919161204.142796-4-justin.he@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190919161204.142796-4-justin.he@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 20, 2019 at 12:12:04AM +0800, Jia He wrote: > @@ -2152,7 +2163,29 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo > */ > if (unlikely(!src)) { > void *kaddr = kmap_atomic(dst); > - void __user *uaddr = (void __user *)(va & PAGE_MASK); > + void __user *uaddr = (void __user *)(addr & PAGE_MASK); > + pte_t entry; > + > + /* On architectures with software "accessed" bits, we would > + * take a double page fault, so mark it accessed here. > + */ > + if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) { > + spin_lock(vmf->ptl); > + if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { > + entry = pte_mkyoung(vmf->orig_pte); > + if (ptep_set_access_flags(vma, addr, > + vmf->pte, entry, 0)) > + update_mmu_cache(vma, addr, vmf->pte); > + } else { > + /* Other thread has already handled the fault > + * and we don't need to do anything. If it's > + * not the case, the fault will be triggered > + * again on the same address. > + */ > + return -1; > + } > + spin_unlock(vmf->ptl); Returning with the spinlock held doesn't normally go very well ;). -- Catalin