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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 54DD2C56201 for ; Fri, 20 Nov 2020 14:36:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E94952224C for ; Fri, 20 Nov 2020 14:36:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="NWbZpQUt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727728AbgKTOgH (ORCPT ); Fri, 20 Nov 2020 09:36:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:33738 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbgKTOgH (ORCPT ); Fri, 20 Nov 2020 09:36:07 -0500 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3C5082236F; Fri, 20 Nov 2020 14:36:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605882966; bh=j2dSYypETbDYVNoDBWsVOOyAKJVVu4Ogy3WRiJXmbGI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NWbZpQUtUGh4S38MxVlOuy+y3ZRHQ+hSU0lessRpwqEV7+WCNXSMp1fUFfrMKd9OH TFMKC+MD6wHULTQjMpUVJDiQmSZt9QXpeyxuEaJQ1LAFkfuHqsrtMGoKfOdxlcr2Li oJC/N5qg2Ae1eefEiIBLHa8KwMUVOHPqVqRv1oPY= From: Will Deacon To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Will Deacon , Catalin Marinas , Yu Zhao , Minchan Kim , Peter Zijlstra , Linus Torvalds , Anshuman Khandual , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org Subject: [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Date: Fri, 20 Nov 2020 14:35:52 +0000 Message-Id: <20201120143557.6715-2-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201120143557.6715-1-will@kernel.org> References: <20201120143557.6715-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pte_accessible() is used by ptep_clear_flush() to figure out whether TLB invalidation is necessary when unmapping pages for reclaim. Although our implementation is correct according to the architecture, returning true only for valid, young ptes in the absence of racing page-table modifications, this is in fact flawed due to lazy invalidation of old ptes in ptep_clear_flush_young() where we elide the expensive DSB instruction for completing the TLB invalidation. Rather than penalise the aging path, adjust pte_accessible() to return true for any valid pte, even if the access flag is cleared. Cc: Fixes: 76c714be0e5e ("arm64: pgtable: implement pte_accessible()") Reported-by: Yu Zhao Signed-off-by: Will Deacon --- arch/arm64/include/asm/pgtable.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 4ff12a7adcfd..1bdf51f01e73 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -115,8 +115,6 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; #define pte_valid(pte) (!!(pte_val(pte) & PTE_VALID)) #define pte_valid_not_user(pte) \ ((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID) -#define pte_valid_young(pte) \ - ((pte_val(pte) & (PTE_VALID | PTE_AF)) == (PTE_VALID | PTE_AF)) #define pte_valid_user(pte) \ ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) @@ -126,7 +124,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; * remapped as PROT_NONE but are yet to be flushed from the TLB. */ #define pte_accessible(mm, pte) \ - (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid_young(pte)) + (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte)) /* * p??_access_permitted() is true for valid user mappings (subject to the -- 2.29.2.454.gaff20da3a2-goog