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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B356FC433EF for ; Thu, 12 May 2022 20:45:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358423AbiELUpO (ORCPT ); Thu, 12 May 2022 16:45:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358432AbiELUpN (ORCPT ); Thu, 12 May 2022 16:45:13 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0581A2300DC for ; Thu, 12 May 2022 13:45:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id E47C6CE2C9C for ; Thu, 12 May 2022 20:45:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 423D0C3411F; Thu, 12 May 2022 20:45:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1652388306; bh=iPY0oGWhzyHYb9lhozTakMvFamT5AENlaEYtT4EuhcU=; h=Date:To:From:Subject:From; b=CYU6ub+Av+zqqJRnXWvQ67wM5HibaVPaglkHKqQpH9SPSq2+sdfUztWt3QhDIBYUC aoETN4cZZ+p097FH36MwtXU+4VVwBx33Ks07SURvnMzh8xyiX9vpjpHtBgYq6kPIye Oc3JMSnxRzqD/yUAXH+eWXhE/7nFedxXHXaec2Vc= Date: Thu, 12 May 2022 13:45:05 -0700 To: mm-commits@vger.kernel.org, paulmck@kernel.org, jhubbard@nvidia.com, david@redhat.com, minchan@kernel.org, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-fix-is_pinnable_page-against-on-cma-page-v5.patch added to mm-unstable branch Message-Id: <20220512204506.423D0C3411F@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5 has been added to the -mm mm-unstable branch. Its filename is mm-fix-is_pinnable_page-against-on-cma-page-v5.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-is_pinnable_page-against-on-cma-page-v5.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Minchan Kim Subject: mm-fix-is_pinnable_page-against-on-cma-page-v5 * clarification why we need READ_ONCE - Paul * Add a comment about READ_ONCE - John Link: https://lkml.kernel.org/r/20220512204143.3961150-1-minchan@kernel.org Signed-off-by: Minchan Kim Cc: "Paul E . McKenney" Cc: John Hubbard Cc: David Hildenbrand Signed-off-by: Andrew Morton --- include/linux/mm.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/include/linux/mm.h~mm-fix-is_pinnable_page-against-on-cma-page-v5 +++ a/include/linux/mm.h @@ -1627,13 +1627,14 @@ static inline bool is_pinnable_page(stru { #ifdef CONFIG_CMA /* - * use volatile to use local variable mt instead of - * refetching mt value. + * Defend against future compiler LTO features, or code refactoring + * that inlines the above function, by forcing a single read. Because, + * this routine races with set_pageblock_migratetype(), and we want to + * avoid reading zero, when actually one or the other flags was set. */ - int __mt = get_pageblock_migratetype(page); int mt = __READ_ONCE(__mt); - if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE) + if (mt & (MIGRATE_CMA | MIGRATE_ISOLATE)) return false; #endif _ Patches currently in -mm which might be from minchan@kernel.org are mm-fix-is_pinnable_page-against-on-cma-page.patch mm-fix-is_pinnable_page-against-on-cma-page-v5.patch mm-dont-be-stuck-to-rmap-lock-on-reclaim-path.patch