From patchwork Fri Jan 24 09:32:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 233122 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=-14.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SIGNED_OFF_BY, 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 20055C35242 for ; Fri, 24 Jan 2020 10:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1EF9208C4 for ; Fri, 24 Jan 2020 10:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579860371; bh=9IHqVBoP5o70HWVnI7Lafl/n/ytmA0G1t8zSPRkbCpU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kSQyTS6zBFQ4+mDPH1OGLj0isePx12RA0z6aZLe9w5nJFI/4RXEWG7e2la/am8f8h zuLSaIau2illx0mpoxWogrX9YDezrfImvUzAyJSYpk+W6NtTc8eH7aTI5Jhdb+Ttcu tRVKF3Pi3BTAw+OiLLhTpSOy1gINkf9BeHIFy7N8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733075AbgAXKGG (ORCPT ); Fri, 24 Jan 2020 05:06:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:42672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389276AbgAXKGF (ORCPT ); Fri, 24 Jan 2020 05:06:05 -0500 Received: from localhost (unknown [145.15.244.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4D2A520718; Fri, 24 Jan 2020 10:06:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579860365; bh=9IHqVBoP5o70HWVnI7Lafl/n/ytmA0G1t8zSPRkbCpU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jSARhf/YyPM9qTm3KoCkSEHMMPXjRRbIj/JRzbY7AP9JyqI6niWBP73AWTdG+lcsG kTWtlDpohi9jyX29Z9A/IlFRGtnq0PfSNnis18MIK5SYmplZj9XaZ97qDwAE6ooURR oHpakyqE1IFoS/rhVOFzaWndbnXpgMFW2y1eBmy8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.14 322/343] net: avoid possible false sharing in sk_leave_memory_pressure() Date: Fri, 24 Jan 2020 10:32:20 +0100 Message-Id: <20200124093002.156697163@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200124092919.490687572@linuxfoundation.org> References: <20200124092919.490687572@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit 503978aca46124cd714703e180b9c8292ba50ba7 ] As mentioned in https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance a C compiler can legally transform : if (memory_pressure && *memory_pressure) *memory_pressure = 0; to : if (memory_pressure) *memory_pressure = 0; Fixes: 0604475119de ("tcp: add TCPMemoryPressuresChrono counter") Fixes: 180d8cd942ce ("foundations of per-cgroup memory pressure controlling.") Fixes: 3ab224be6d69 ("[NET] CORE: Introducing new memory accounting interface.") Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/core/sock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/sock.c b/net/core/sock.c index 90ccbbf9e6b00..03ca2f638eb4a 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2165,8 +2165,8 @@ static void sk_leave_memory_pressure(struct sock *sk) } else { unsigned long *memory_pressure = sk->sk_prot->memory_pressure; - if (memory_pressure && *memory_pressure) - *memory_pressure = 0; + if (memory_pressure && READ_ONCE(*memory_pressure)) + WRITE_ONCE(*memory_pressure, 0); } }