From patchwork Tue Apr 20 15:00:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Rapoport X-Patchwork-Id: 12214485 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=-16.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 A95E7C433B4 for ; Tue, 20 Apr 2021 15:01:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3811E613CF for ; Tue, 20 Apr 2021 15:01:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3811E613CF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 958BA6B006E; Tue, 20 Apr 2021 11:01:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 932EC6B0070; Tue, 20 Apr 2021 11:01:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7ABB36B0071; Tue, 20 Apr 2021 11:01:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id 61C9B6B006E for ; Tue, 20 Apr 2021 11:01:22 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 23CEC4DD0 for ; Tue, 20 Apr 2021 15:01:22 +0000 (UTC) X-FDA: 78053058804.29.D73C46E Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP id 09A21E0020DB for ; Tue, 20 Apr 2021 15:01:19 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 755236024A; Tue, 20 Apr 2021 15:01:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618930876; bh=YWZWy73tqvCKAkk9V8YhZ1ig6ylDklRIyvUgj9G3Qqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AvfI48GQEUCgATQPRlh15VnMXoZu3ZrAzlargumz56omxGHSsgZ+X25Jm4uXtaP9d ZD8syRRrFQUMViRfNfGpwdlmr2B9H0YhE5g8MUwgj77Qx2P2KF7DwOhOnpLzhAnjUK 78OGltrp46CIQR/BM0JZX4HYJTh1d4/YWOs9Mpqe8qVUCcsHXj6tcbDuq5s+irERZY 1RNUZhlewg3bN1Hm3jmlnu1QSIsyknis7N9xgq+PavSOMRHXHp3DG9eKucgLw1TPNM wzWKpK6wyMtFcYr3RYfN9G6HVQdYyX+LHEnbZLQi8iWG535paN1bFibNloawn8SNOc xGt5UMlHKdsOQ== 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 v3 1/2] secretmem/gup: don't check if page is secretmem without reference Date: Tue, 20 Apr 2021 18:00:48 +0300 Message-Id: <20210420150049.14031-2-rppt@kernel.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20210420150049.14031-1-rppt@kernel.org> References: <20210420150049.14031-1-rppt@kernel.org> MIME-Version: 1.0 X-Rspamd-Queue-Id: 09A21E0020DB X-Stat-Signature: f13ykygeop6jum64obqw4yskp6ccjrfh X-Rspamd-Server: rspam02 Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618930879-136394 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: 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 Reviewed-by: David Hildenbrand --- mm/gup.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index c3a17b189064..6515f82b0f32 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2080,13 +2080,15 @@ 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 (unlikely(page_is_secretmem(page))) { + put_compound_head(head, 1, flags); + goto pte_unmap; + } + if (unlikely(pte_val(pte) != pte_val(*ptep))) { put_compound_head(head, 1, flags); goto pte_unmap;