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authorGautham R Shenoy <ego@in.ibm.com>2008-09-06 09:20:23 (GMT)
committerIngo Molnar <mingo@elte.hu>2008-09-06 14:53:34 (GMT)
commit38736f475071b80b66be28af7b44c854073699cc (patch)
tree853b00d9fcf27093f75dbfe7d38922792c2c1a04 /kernel
parent7f79d852ed30a06eebf7497afe9334a726db3d40 (diff)
downloadlinux-38736f475071b80b66be28af7b44c854073699cc.tar.xz
sched: fix __load_balance_iterator() for cfq with only one task
The __load_balance_iterator() returns a NULL when there's only one sched_entity which is a task. It is caused by the following code-path. /* Skip over entities that are not tasks */ do { se = list_entry(next, struct sched_entity, group_node); next = next->next; } while (next != &cfs_rq->tasks && !entity_is_task(se)); if (next == &cfs_rq->tasks) return NULL; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This will return NULL even when se is a task. As a side-effect, there was a regression in sched_mc behavior since 2.6.25, since iter_move_one_task() when it calls load_balance_start_fair(), would not get any tasks to move! Fix this by checking if the last entity was a task or not. Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched_fair.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 8264bb5..a10ac0b 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1458,7 +1458,7 @@ __load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
next = next->next;
} while (next != &cfs_rq->tasks && !entity_is_task(se));
- if (next == &cfs_rq->tasks)
+ if (next == &cfs_rq->tasks && !entity_is_task(se))
return NULL;
cfs_rq->balance_iterator = next;