From: Vineeth Pillai <virem...@linux.microsoft.com> During a CPU hotplug event, schedule would be called with the hotplugged CPU not in the cpumask. So use for_each_cpu(_wrap)_or to include the current cpu in the task pick loop.
Signed-off-by: Vineeth Pillai <virem...@linux.microsoft.com> Co-developed-by: Joel Fernandes (Google) <j...@joelfernandes.org> Signed-off-by: Joel Fernandes (Google) <j...@joelfernandes.org> --- kernel/sched/core.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ff13254ed317..3e9df8221c62 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4663,7 +4663,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) /* reset state */ rq->core->core_cookie = 0UL; - for_each_cpu(i, smt_mask) { + for_each_cpu_or(i, smt_mask, cpumask_of(cpu)) { struct rq *rq_i = cpu_rq(i); trace_printk("CPU %d is in smt_mask, resetting\n", i); @@ -4685,7 +4685,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) */ for_each_class(class) { again: - for_each_cpu_wrap(i, smt_mask, cpu) { + for_each_cpu_wrap_or(i, smt_mask, cpumask_of(cpu), cpu) { struct rq *rq_i = cpu_rq(i); struct task_struct *p; @@ -4774,6 +4774,9 @@ next_class:; rq->core->core_pick_seq = rq->core->core_task_seq; next = rq->core_pick; rq->core_sched_seq = rq->core->core_pick_seq; + + /* Something should have been selected for current CPU */ + WARN_ON_ONCE(!next); trace_printk("picked: %s/%d %lx\n", next->comm, next->pid, next->core_cookie); /* @@ -4784,7 +4787,7 @@ next_class:; * their task. This ensures there is no inter-sibling overlap between * non-matching user state. */ - for_each_cpu(i, smt_mask) { + for_each_cpu_or(i, smt_mask, cpumask_of(cpu)) { struct rq *rq_i = cpu_rq(i); WARN_ON_ONCE(!rq_i->core_pick); -- 2.28.0.220.ged08abb693-goog