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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 7A966C63798 for ; Thu, 22 Jul 2021 16:36:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 644F061369 for ; Thu, 22 Jul 2021 16:36:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232714AbhGVP4I (ORCPT ); Thu, 22 Jul 2021 11:56:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:58980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231152AbhGVPyu (ORCPT ); Thu, 22 Jul 2021 11:54:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0300361362; Thu, 22 Jul 2021 16:35:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626971725; bh=ZmT+drcZBBH0K4+KL76eoM8ZjibvMPXxGj91oQO4ZK4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2cGvHplJZNiXbKNIoLi3YCpWBia5M2tO8+msS9B9iLas2d45BD5GMxMc8T75O21hz 6kU7vEqxYuxToI+4tKTAoulyGI8WtZ+7I4+M9je526obkte/fKbZxvwnz0kjbqDegm KlX2CSsCzrwPuaP9RnBtN5b2Nh4GS7J7oEHV//x4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Odin Ugedal , "Peter Zijlstra (Intel)" , Ben Segall , Sasha Levin Subject: [PATCH 5.4 42/71] sched/fair: Fix CFS bandwidth hrtimer expiry type Date: Thu, 22 Jul 2021 18:31:17 +0200 Message-Id: <20210722155619.270341479@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210722155617.865866034@linuxfoundation.org> References: <20210722155617.865866034@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 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 d2ba080ea742..74cb20f32f72 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4786,7 +4786,7 @@ 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)) @@ -4794,7 +4794,7 @@ 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