The patch below does not apply to the 3.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 0372dd2736e02672ac6e189c31f7d8c02ad543cd Mon Sep 17 00:00:00 2001 From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Fri, 14 Apr 2017 17:24:02 +0200 Subject: [PATCH] sched/topology: Fix building of overlapping sched-groups 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@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Fixes: e3589f6c81e4 ("sched: Allow for overlapping sched_domain spans") Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index d786d45c44d9..921dedde2ee1 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -566,7 +566,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) 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))