Patch "sched/topology: Fix building of overlapping sched-groups" has been added to the 4.9-stable tree

Patch "sched/topology: Fix building of overlapping sched-groups" has been added to the 4.9-stable tree

[gregkh]

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 4.9-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-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0372dd2736e02672ac6e189c31f7d8c02ad543cd Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 14 Apr 2017 17:24:02 +0200
Subject: sched/topology: Fix building of overlapping sched-groups

From: Peter Zijlstra <peterz@infradead.org>

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)

Debugged-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: e3589f6c81e4 ("sched: Allow for overlapping sched_domain spans")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6148,7 +6148,7 @@ 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 peterz@infradead.org are

queue-4.9/revert-sched-core-optimize-sched_smt.patch
queue-4.9/sched-topology-fix-building-of-overlapping-sched-groups.patch
queue-4.9/sched-topology-fix-overlapping-sched_group_mask.patch
queue-4.9/kernel-extable.c-mark-core_kernel_text-notrace.patch
queue-4.9/tools-lib-lockdep-reduce-max_lock_depth-to-avoid-overflowing-lock_chain-depth.patch