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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 E8834C2D0C2 for ; Fri, 6 Dec 2019 13:57:41 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B00D220706 for ; Fri, 6 Dec 2019 13:57:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="CFdESAg+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B00D220706 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=qeyiUSVoD9mkHyS/WH+aNn1fnJJEKRBc4eJCN2Ggx1E=; b=CFdESAg+ND/5Bz EP3jcCMOOeWKFphvkZ68nNuFCvd8U4Duc6ud3OWHuE0pqBRJ9koLz/ThjOtNYwcXKLklzF6HiLadQ xkcZsQQu5CRrG7Lwewp99+3WSgWzg6dNcC2eHxoYFw7bgDVpJAI5OCNvIpUm3VFM+dUvVJGSabBBx 9rk21AAkNZPLu851rvLurgK9hw/8adm8ts5AENo1WraZ1D/1atfn1x4T5Ki6tajQYYxN+IHMnxua6 NCOpvfxoojZFFmCyTu6I6wr6Ovi6lswvye+5R/sOBauvuc1mbtRNzRq06TMyrblTydXyf80WvfMzh r48F4nT3i5pJdj+Icvag==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1idE70-0007Bm-El; Fri, 06 Dec 2019 13:57:38 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1idE3q-00032B-B7 for linux-arm-kernel@lists.infradead.org; Fri, 06 Dec 2019 13:54:23 +0000 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 D42ED1FB; Fri, 6 Dec 2019 05:54:21 -0800 (PST) Received: from e112269-lin.cambridge.arm.com (e112269-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 54C263F718; Fri, 6 Dec 2019 05:54:19 -0800 (PST) From: Steven Price To: Andrew Morton , linux-mm@kvack.org Subject: [PATCH v16 13/25] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Date: Fri, 6 Dec 2019 13:53:04 +0000 Message-Id: <20191206135316.47703-14-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191206135316.47703-1-steven.price@arm.com> References: <20191206135316.47703-1-steven.price@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191206_055422_444962_DC162E59 X-CRM114-Status: GOOD ( 14.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , x86@kernel.org, Arnd Bergmann , Ard Biesheuvel , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-kernel@vger.kernel.org, Steven Price , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Ingo Molnar , Borislav Petkov , Andy Lutomirski , "H. Peter Anvin" , James Morse , Thomas Gleixner , Will Deacon , linux-arm-kernel@lists.infradead.org, "Liang, Kan" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org walk_page_range_novma() can be used to walk page tables or the kernel or for firmware. These page tables may contain entries that are not backed by a struct page and so it isn't (in general) possible to take the PTE lock for the pte_entry() callback. So update walk_pte_range() to only take the lock when no_vma==false and add a comment explaining the difference to walk_page_range_novma(). Signed-off-by: Steven Price --- mm/pagewalk.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index efa464cf079b..1b9a3ba24c51 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -10,9 +10,10 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte_t *pte; int err = 0; const struct mm_walk_ops *ops = walk->ops; - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); - pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); + pte = walk->no_vma ? pte_offset_map(pmd, addr) : + pte_offset_map_lock(walk->mm, pmd, addr, &ptl); for (;;) { err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk); if (err) @@ -23,7 +24,9 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte++; } - pte_unmap_unlock(pte, ptl); + if (!walk->no_vma) + spin_unlock(ptl); + pte_unmap(pte); return err; } @@ -383,6 +386,12 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, return err; } +/* + * Similar to walk_page_range() but can walk any page tables even if they are + * not backed by VMAs. Because 'unusual' entries may be walked this function + * will also not lock the PTEs for the pte_entry() callback. This is useful for + * walking the kernel pages tables or page tables for firmware. + */ int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, void *private) -- 2.20.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel