From patchwork Tue Jan 18 23:05:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Collingbourne X-Patchwork-Id: 533484 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F0C5C433EF for ; Tue, 18 Jan 2022 23:05:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230234AbiARXFw (ORCPT ); Tue, 18 Jan 2022 18:05:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349822AbiARXFw (ORCPT ); Tue, 18 Jan 2022 18:05:52 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17E8DC06161C for ; Tue, 18 Jan 2022 15:05:52 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id k189-20020a25c6c6000000b0061274ece35eso1045004ybf.22 for ; Tue, 18 Jan 2022 15:05:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=l6hbRAzMlKkhDXyQqtvv9DAL8rlD+/FgUl4MA5CnPm8=; b=nKkhAP96OCYA4M4x80g28cPG8G8ErsxJaS13Ynx/835zUQOktZxpfEllu14SNaW6ZN qXjKLzaRdYhy9PJXVwbP+2Jf1b9hP+lSMPoBwidlUYmXQWDyTWVpJInj3fq7WDafuxTa iIoMeNcwjnN6Ys6MwD+AtzizkCx/n3FuS7igc6T6IDDeJFG6FQ777u1Qd2e2Lzw62juQ 5JRnEs8RrSNVwLs7Y+HjIBoRj9LPNtc4cLGAxoZ+I0F6hnJ9Xco3AK9rmu4dY5TIwj4G GtXcDJ7/CuGC+07RaUPJ0D9cxTZnpUu/BKnZULfy5igYqfOQlEk7iMU8tfsSEEyXIhRU O4dA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=l6hbRAzMlKkhDXyQqtvv9DAL8rlD+/FgUl4MA5CnPm8=; b=ZghffjGi5pAjZsu4sZ49yLZryWBOwp1JaJ4cv6f57G+upEfqcu/3odvxI9fPWkzdY0 IwfupQsFbTNnbonVz1N5M5T9HY9hROl5uDaZof8crty8SqLs7oq7qpsEBB8ac+2eHRwB s4Dm58P3aKFePEHU1DPFnO+v1qInS86H7DWAmoAJ3LBQFZONg9CZhzPjhyeHy40P9y6Q 1YZB2DefXpJwhVdBBcZq1Ht0w6xcwHF3U45BDQjjHy6vHVSAu1T+dXNuxE8l1J7lQy/G /eVz1RWjlrQzmDms44fJAQvPYkxm/fkAZNLNXldMxXNbsRHABs+4Mx/yR2R8HQJWFo8n DTAg== X-Gm-Message-State: AOAM531vyew3bBE8lujIs59zcY8XyICaJwNUTP6MK6i+ks+KKEbZAF4S pfsyFh896eyIpJqq1j4eMKr7kO4= X-Google-Smtp-Source: ABdhPJyPdrj4Y716RGRIKh5U4LkCBP0FlJ7hNEnEfsKuQQvudDZBs5KtsbgYz/GzyiJmv9fnRvg5DBM= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2ce:200:1443:965d:6393:cd60]) (user=pcc job=sendgmr) by 2002:a25:a047:: with SMTP id x65mr37555287ybh.370.1642547151356; Tue, 18 Jan 2022 15:05:51 -0800 (PST) Date: Tue, 18 Jan 2022 15:05:39 -0800 Message-Id: <20220118230539.323058-1-pcc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.34.1.703.g22d0c6ccf7-goog Subject: [PATCH] mm/mmzone.c: fix page_cpupid_xchg_last() to READ_ONCE() the page flags From: Peter Collingbourne To: Andrey Konovalov , Andrew Morton Cc: Peter Collingbourne , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Mel Gorman , stable@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org After submitting a patch with a compare-exchange loop similar to this one to set the KASAN tag in the page flags, Andrey Konovalov pointed out that we should be using READ_ONCE() to read the page flags. Fix it here. Fixes: 75980e97dacc ("mm: fold page->_last_nid into page->flags where possible") Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I2e1f5b5b080ac9c4e0eb7f98768dba6fd7821693 Cc: stable@vger.kernel.org --- mm/mmzone.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/mmzone.c b/mm/mmzone.c index eb89d6e018e2..f84b84b0d3fc 100644 --- a/mm/mmzone.c +++ b/mm/mmzone.c @@ -90,7 +90,7 @@ int page_cpupid_xchg_last(struct page *page, int cpupid) int last_cpupid; do { - old_flags = flags = page->flags; + old_flags = flags = READ_ONCE(page->flags); last_cpupid = page_cpupid_last(page); flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);