linux-kernel - [PATCH 20/39] autonuma: avoid CFS select_task_rq

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Message-Id: <1332783986-24195-21-git-send-email-aarcange@redhat.com>
Date:	Mon, 26 Mar 2012 19:46:07 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:	Hillf Danton <dhillf@...il.com>, Dan Smith <danms@...ibm.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, Paul Turner <pjt@...gle.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Mike Galbraith <efault@....de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Bharata B Rao <bharata.rao@...il.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH 20/39] autonuma: avoid CFS select_task_rq_fair to return -1

Fix to avoid -1 retval.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 kernel/sched/fair.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 94340c7..25e9e5b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2769,6 +2769,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
 		goto unlock;
 	}
 
+	prev_cpu = new_cpu;
 	while (sd) {
 		int load_idx = sd->forkexec_idx;
 		struct sched_group *group;
@@ -2792,6 +2793,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
 		if (new_cpu == -1 || new_cpu == cpu) {
 			/* Now try balancing at a lower domain level of cpu */
 			sd = sd->child;
+			new_cpu = prev_cpu;
 			continue;
 		}
 
@@ -2810,6 +2812,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
 unlock:
 	rcu_read_unlock();
 
+	BUG_ON(new_cpu < 0);
 	return new_cpu;
 }
 #endif /* CONFIG_SMP */
--
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