From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F5E52572 for ; Tue, 18 Apr 2023 12:46:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 222CFC433D2; Tue, 18 Apr 2023 12:46:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681822006; bh=s4dBXLKRkJ8O07bMKNZikRQ+iaJQvsGa2Vk/OTY9CiU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dCIuvZgSbJnFnXqspuh01t66aMTwsNTiTdWeHJSrlq+ZRvyWhdUUaGXuVwrsJjHAl DBKhw3VCLVKPOQ/BvYYnNb7DAZY4/P8pSjkRNhE3pttzrXwnEVWknCQZtnkXnhFMkN v4QINzXyWeqf3Yio8P90SX0wOjeI8tWunLa3eXTg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tingjia Cao , Vincent Guittot , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 6.1 122/134] sched/fair: Fix imbalance overflow Date: Tue, 18 Apr 2023 14:22:58 +0200 Message-Id: <20230418120317.439125199@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120313.001025904@linuxfoundation.org> References: <20230418120313.001025904@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Vincent Guittot [ Upstream commit 91dcf1e8068e9a8823e419a7a34ff4341275fb70 ] When local group is fully busy but its average load is above system load, computing the imbalance will overflow and local group is not the best target for pulling this load. Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()") Reported-by: Tingjia Cao Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Tested-by: Tingjia Cao Link: https://lore.kernel.org/lkml/CABcWv9_DAhVBOq2=W=2ypKE9dKM5s2DvoV8-U0+GDwwuKZ89jQ@mail.gmail.com/T/ Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 88821ab009b30..ec2d913280e6a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10041,6 +10041,16 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s sds->avg_load = (sds->total_load * SCHED_CAPACITY_SCALE) / sds->total_capacity; + + /* + * If the local group is more loaded than the average system + * load, don't try to pull any tasks. + */ + if (local->avg_load >= sds->avg_load) { + env->imbalance = 0; + return; + } + } /* -- 2.39.2