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authorLi Zefan <lizf@cn.fujitsu.com>2008-11-06 09:45:16 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2008-12-13 15:29:30 -0800
commit1c03c0828f200dfde456836fe69febb72979b5c7 (patch)
tree821bb7b5c30e60cda866bc93cfc02eb9b341f738 /kernel
parent8695c0e41ee6fcfce99b7335565d6b1a2e2fbda8 (diff)
sched: fix a bug in sched domain degenerate
commit f29c9b1ccb52904ee442a933cf3dee628f9f4e62 upstream. Impact: re-add incorrectly eliminated sched domain layers (1) on i386 with SCHED_SMT and SCHED_MC enabled # mount -t cgroup -o cpuset xxx /mnt # echo 0 > /mnt/cpuset.sched_load_balance # mkdir /mnt/0 # echo 0 > /mnt/0/cpuset.cpus # dmesg CPU0 attaching sched-domain: domain 0: span 0 level CPU groups: 0 (2) on i386 with SCHED_MC enabled but SCHED_SMT disabled # same with (1) # dmesg CPU0 attaching NULL sched-domain. The bug is that some sched domains may be skipped unintentionally when degenerating (optimizing) sched domains. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index a992cbe01c73..719f8ba2c35f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6802,15 +6802,17 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
struct sched_domain *tmp;
/* Remove the sched domains which do not contribute to scheduling. */
- for (tmp = sd; tmp; tmp = tmp->parent) {
+ for (tmp = sd; tmp; ) {
struct sched_domain *parent = tmp->parent;
if (!parent)
break;
+
if (sd_parent_degenerate(tmp, parent)) {
tmp->parent = parent->parent;
if (parent->parent)
parent->parent->child = tmp;
- }
+ } else
+ tmp = tmp->parent;
}
if (sd && sd_degenerate(sd)) {