From patchwork Tue Apr 20 13:16:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12214277 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=-17.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 73D19C433ED for ; Tue, 20 Apr 2021 13:18:29 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 BA13161155 for ; Tue, 20 Apr 2021 13:18:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BA13161155 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ulqJh5V0azU5o+dz3YuEd2z1gANTPwy+AGBRaiGYpCk=; b=EWf7pOrs3z63sjmep2lXZYlCW bItuA4o2txrsezuL9MebcVzaXJkqXSaU6Pll6ksgv8LadVbTCVv+5QhO0eNNywS/J12dwCAw1R68c sMl7PGEYOojSchZNRPzsYSDsfj7TPxT4Fp1zS7l32Bqz5Ty3xu7cXAXLwU98SbunUi1KWYVmi728J 0zOWMshOrMfC8qsUhK4oISap8t/t89y6tdZ2s4T79QODQlsakA8x5Z7Py8862H3KHdgrntk/W1uuD RP1iyHwaWM6+52slSEyBSprB8p5eqi9DyS+aDIHz/f3Ui72Zriil37oUtwohMAebAZND14yNQ3Cjn E5Jhig/Cg==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lYqFG-00CB99-LY; Tue, 20 Apr 2021 13:16:51 +0000 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lYqF8-00CB8M-Ju; Tue, 20 Apr 2021 13:16:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=2UiMd1x2iPg5BHSmMMcJrxFoD7KyHYuCPHs/JKxkkTI=; b=UEDgPm4KfI9CYHvgndsnu+Tnii Tw0K0YLdicd1EOT76gC9eXwFGYbUkzUUa56jWuAvzr0XRCFskbE+Ap5QEjRRyU+7Umx+iwvZDljCK P6RCEzk5YY2pcQDXTSpE5n9DNlNVBeIzjNrNemVVohMl1RryFu5N1QqZHEZC26T+fGmNTerpzdy3p 1PLz3XOcBGS1pZ/IPraouySqrXWmcK6gD/+C032ie55fvAWTNzZaAvqU2VrE1ZlEyBGkiQ9JVBn6k O2zB6emM4T3mmTaHTK4YLlFJC2F5WKJBlo2GFmFu6dK6OF5U7/GDfIF4ZUI8U5xg3lwlAxugYzhXE +0d0ro6g==; Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lYqF6-00C8Ct-6o; Tue, 20 Apr 2021 13:16:41 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8D3E9613CD; Tue, 20 Apr 2021 13:16:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618924599; bh=WQBjtjBUVixKPUq09lDhJ2RWgVokupnypM/eycKpBe4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KLusc3hvcK/USIRTI1/AA31CBHshBIRyZKJvd5mzmsf8uSSJ7TpzKDUsknaC7MPq6 eN0zAy+9/IAGzPjtf0706PNPT2er4LIkgsjACRHnJ0RD6mEJSD9zoue15HlmXFbsNB WGr5S/g/5n5tBlMAVJCDdPgvHQnj5JM/Bjkejl8nPPCZ8wGk0lluRfswUy871QdR0G NvuSLdYZOYvhOTbadz3yEZRjXbepapK8sotHUAsbDxshP5vjW7LQpXxOenROX7IQQr FdwihTAykTp4q2B0yXS34iR+4uoUJCi072sqeX6ixjq5AcceB0CrHyE/nOjCJknzzP mVOEnaY9ajjYg== From: Mike Rapoport To: Andrew Morton Cc: Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Matthew Garrett , Mark Rutland , Michal Hocko , Mike Rapoport , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , "Rafael J. Wysocki" , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , Yury Norov , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: [PATCH v2 1/2] secretmem/gup: don't check if page is secretmem without reference Date: Tue, 20 Apr 2021 16:16:08 +0300 Message-Id: <20210420131611.8259-2-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20210420131611.8259-1-rppt@kernel.org> References: <20210420131611.8259-1-rppt@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210420_061640_305405_8C3B2557 X-CRM114-Status: GOOD ( 13.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Mike Rapoport The check in gup_pte_range() whether a page belongs to a secretmem mapping is performed before grabbing the page reference. To avoid potential race move the check after try_grab_compound_head(). Signed-off-by: Mike Rapoport --- mm/gup.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index c3a17b189064..4b58c016e949 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2080,13 +2080,13 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end, VM_BUG_ON(!pfn_valid(pte_pfn(pte))); page = pte_page(pte); - if (page_is_secretmem(page)) - goto pte_unmap; - head = try_grab_compound_head(page, 1, flags); if (!head) goto pte_unmap; + if (page_is_secretmem(page)) + goto pte_unmap; + if (unlikely(pte_val(pte) != pte_val(*ptep))) { put_compound_head(head, 1, flags); goto pte_unmap;