Re: [powerpc][next-20210621] WARNING at kernel/sched/fair.c:3277 during boot

From: Odin Ugedal <odin@uged.al>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>,
	Odin Ugedal <odin@uged.al>,
	Linux Next Mailing List <linux-next@vger.kernel.org>,
	linuxppc-dev@lists.ozlabs.org,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [powerpc][next-20210621] WARNING at kernel/sched/fair.c:3277 during boot
Date: Wed, 23 Jun 2021 14:18:16 +0200	[thread overview]
Message-ID: <CAFpoUr01xb9ZJF9mb2nmZDpUHXFH3VSbY3AU8-1owV-_7wVTPg@mail.gmail.com> (raw)
In-Reply-To: <20210623120835.GB29143@vingu-book>

Hi,

Wouldn't the attached diff below also help when load is removed,
Vincent? Isn't there a theoretical chance that x_sum ends up at zero
while x_load ends up as a positive value (without this patch)? Can
post as a separate patch if it works for Sachin.

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bfaa6e1f6067..def48bc2e90b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3688,15 +3688,15 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)

                r = removed_load;
                sub_positive(&sa->load_avg, r);
-               sub_positive(&sa->load_sum, r * divider);
+               sa->load_sum = sa->load_avg * divider;

                r = removed_util;
                sub_positive(&sa->util_avg, r);
-               sub_positive(&sa->util_sum, r * divider);
+               sa->util_sum = sa->util_avg * divider;

                r = removed_runnable;
                sub_positive(&sa->runnable_avg, r);
-               sub_positive(&sa->runnable_sum, r * divider);
+               sa->runnable_sum = sa->runnable_avg * divider;

                /*
                 * removed_runnable is the unweighted version of
removed_load so we
