The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 48a723d23b0d957e5b5861b974864e53c6841de8 Gitweb: https://git.kernel.org/tip/48a723d23b0d957e5b5861b974864e53c6841de8 Author: Valentin Schneider <valentin.schneider@xxxxxxx> AuthorDate: Mon, 04 Nov 2019 00:39:06 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Fri, 15 Nov 2019 11:02:20 +01:00 sched/topology, cpuset: Account for housekeeping CPUs to avoid empty cpumasks Michal noted that a cpuset's effective_cpus can be a non-empy mask, but because of the masking done with housekeeping_cpumask(HK_FLAG_DOMAIN) further down the line, we can still end up with an empty cpumask being passed down to partition_sched_domains_locked(). Do the proper thing and don't just check the mask is non-empty - check that its intersection with housekeeping_cpumask(HK_FLAG_DOMAIN) is non-empty. Reported-by: Michal Koutný <mkoutny@xxxxxxxx> Signed-off-by: Valentin Schneider <valentin.schneider@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Dietmar.Eggemann@xxxxxxx Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: hannes@xxxxxxxxxxx Cc: lizefan@xxxxxxxxxx Cc: morten.rasmussen@xxxxxxx Cc: qperret@xxxxxxxxxx Cc: tj@xxxxxxxxxx Cc: vincent.guittot@xxxxxxxxxx Fixes: cd1cb3350561 ("sched/topology: Don't try to build empty sched domains") Link: https://lkml.kernel.org/r/20191104003906.31476-1-valentin.schneider@xxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/cgroup/cpuset.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index c87ee64..e4c1078 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -798,8 +798,14 @@ static int generate_sched_domains(cpumask_var_t **domains, cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus)) continue; + /* + * Skip cpusets that would lead to an empty sched domain. + * That could be because effective_cpus is empty, or because + * it's only spanning CPUs outside the housekeeping mask. + */ if (is_sched_load_balance(cp) && - !cpumask_empty(cp->effective_cpus)) + cpumask_intersects(cp->effective_cpus, + housekeeping_cpumask(HK_FLAG_DOMAIN))) csa[csn++] = cp; /* skip @cp's subtree if not a partition root */
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