Patch "sched/topology: Fix building of overlapping sched-groups" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

sched/topology: Fix building of overlapping sched-groups

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sched-topology-fix-building-of-overlapping-sched-groups.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Peter Zijlstra <[email protected]>
Date: Fri, 14 Apr 2017 17:24:02 +0200
Subject: sched/topology: Fix building of overlapping sched-groups

From: Peter Zijlstra <[email protected]>

commit 0372dd2736e02672ac6e189c31f7d8c02ad543cd upstream.

When building the overlapping groups, we very obviously should start with the previous domain of _this_ @cpu, not CPU-0.

This can be readily demonstrated with a topology like:

node 0 1 2 3

    0:  10  20  30  20
    1:  20  10  20  30
    2:  30  20  10  20
    3:  20  30  20  10

Where (for example) CPU1 ends up generating the following nonsensical groups:

[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 2 0
[] domain 1: span 0-3 level NUMA
[] groups: 1-3 (cpu_capacity = 3072) 0-1,3 (cpu_capacity = 3072)

Where the fact that domain 1 doesn't include a group with span 0-2 is the obvious fail.

With patch this looks like:

[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 0 2
[] domain 1: span 0-3 level NUMA
[] groups: 0-2 (cpu_capacity = 3072) 0,2-3 (cpu_capacity = 3072)

---
 kernel/sched/topology.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -525,7 +525,7 @@ build_overlap_sched_groups(struct sched_
 
 	cpumask_clear(covered);
 
-	for_each_cpu(i, span) {
+	for_each_cpu_wrap(i, span, cpu) {
 		struct cpumask *sg_span;
 
 		if (cpumask_test_cpu(i, covered))

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/efi-process-the-memattr-table-only-if-efi_memmap-is-enabled.patch queue-4.12/sched-headers-uapi-fix-linux-sched-types.h-userspace-compilation-errors.patch queue-4.12/x86-xen-efi-initialize-only-the-efi-struct-members-used-by-xen.patch queue-4.12/compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch queue-4.12/sched-topology-fix-building-of-overlapping-sched-groups.patch queue-4.12/sched-topology-fix-overlapping-sched_group_mask.patch queue-4.12/kernel-extable.c-mark-core_kernel_text-notrace.patch queue-4.12/tools-lib-lockdep-reduce-max_lock_depth-to-avoid-overflowing-lock_chain-depth.patch