2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Li Zefan 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 Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar Cc: Gregory Haskins Signed-off-by: Greg Kroah-Hartman --- kernel/sched.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6802,15 +6802,17 @@ cpu_attach_domain(struct sched_domain *s 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)) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/