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 75E822572 for ; Tue, 18 Apr 2023 12:41:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C7616C433EF; Tue, 18 Apr 2023 12:41:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681821669; bh=3x6INlL+EyQvHlMmm7eq6/GZXrYaDgUt1YGPrTJfwUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D+M9EBGsK7hJi3YZAuF1B8G3QNvrS77nRUrxuM9HE4ZI+zG9crPT8FP5olJUiOouD lKGGzSNeuOXrOxuxL+zDHV/3OFBo3Uykjz0sSp7B0cusp6iBx2BTfnbfa/4zbWkmtR U2drEuLznUSr72IBcmm3KsMgqyEryZ/mh6Ix1HG0= 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 5.15 71/91] sched/fair: Fix imbalance overflow Date: Tue, 18 Apr 2023 14:22:15 +0200 Message-Id: <20230418120308.022151080@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120305.520719816@linuxfoundation.org> References: <20230418120305.520719816@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 024d18d85526d..7ac00dede846c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -9647,6 +9647,16 @@ 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