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 X-Spam-Level: X-Spam-Status: No, score=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 5ED6AC47E53 for ; Wed, 14 Jul 2021 20:02:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 483DB61260 for ; Wed, 14 Jul 2021 20:02:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242396AbhGNUEt (ORCPT ); Wed, 14 Jul 2021 16:04:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:48560 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237450AbhGNTvA (ORCPT ); Wed, 14 Jul 2021 15:51:00 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 500AC613CA; Wed, 14 Jul 2021 19:48:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626292085; bh=6Y9W5CE7mr7KW6UlyBi2buo11m/O+O5p28a1c+IyMfk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o9s8ao6ah+yuFJ1bZDuTPMz09qp6Sm2n366i+BuwjFvlv/KwnqXMrXxXuB8xKhVaz 2Tv7AX1HoMtKQiOYmM9PHCLg1LgbxkU3/L28O9+p9GPDmBlPz00XpMzQgxyFrnsS1Z JEcV0zOPZ2ykrBkCdAp73SQukJaYMarTi6GB3m0yURwIo4ov++wifP7KNytN6n/bhZ bgOvmK3ImGtoAMUVi8EPD8YMU49jQFE5Luh5nQyZObiVAYJluvxA8e0bTVa4+POtyw Se1q60/szZrA87bIHcr2IKDGtWDF8rP0fc09NFJk1neGg9Op5mNCFLYKoBC5sLuc2A e0WqHXk7PRwOA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Odin Ugedal , Peter Zijlstra , Ben Segall , Sasha Levin Subject: [PATCH AUTOSEL 4.14 28/28] sched/fair: Fix CFS bandwidth hrtimer expiry type Date: Wed, 14 Jul 2021 15:47:23 -0400 Message-Id: <20210714194723.55677-28-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210714194723.55677-1-sashal@kernel.org> References: <20210714194723.55677-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Odin Ugedal [ Upstream commit 72d0ad7cb5bad265adb2014dbe46c4ccb11afaba ] The time remaining until expiry of the refresh_timer can be negative. Casting the type to an unsigned 64-bit value will cause integer underflow, making the runtime_refresh_within return false instead of true. These situations are rare, but they do happen. This does not cause user-facing issues or errors; other than possibly unthrottling cfs_rq's using runtime from the previous period(s), making the CFS bandwidth enforcement less strict in those (special) situations. Signed-off-by: Odin Ugedal Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Link: https://lore.kernel.org/r/20210629121452.18429-1-odin@uged.al Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 37ac76dce908..3ff60230710c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4464,7 +4464,7 @@ static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) { struct hrtimer *refresh_timer = &cfs_b->period_timer; - u64 remaining; + s64 remaining; /* if the call-back is running a quota refresh is already occurring */ if (hrtimer_callback_running(refresh_timer)) @@ -4472,7 +4472,7 @@ static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) /* is a quota refresh about to occur? */ remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer)); - if (remaining < min_expire) + if (remaining < (s64)min_expire) return 1; return 0; -- 2.30.2