[PATCH 03/17] sched/core: Dont allow to use CPU marked as paravirt
From: Shrikanth Hegde <hidden>
Date: 2025-11-19 12:45:41
Also in:
lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Don't allow a paravirt CPU to be used while looking for a CPU to use. Push task mechanism uses stopper thread which going to call select_fallback_rq and use this mechanism to avoid picking a paravirt CPU. Signed-off-by: Shrikanth Hegde <redacted> --- kernel/sched/core.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 40db5e659994..90fc04d84b74 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -2397,8 +2397,13 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu) return cpu_online(cpu); /* Non kernel threads are not allowed during either online or offline. */ - if (!(p->flags & PF_KTHREAD)) - return cpu_active(cpu); + if (!(p->flags & PF_KTHREAD)) { + /* A user thread shouldn't be allowed on a paravirt cpu */ + if (cpu_paravirt(cpu)) + return false; + else + return cpu_active(cpu); + } /* KTHREAD_IS_PER_CPU is always allowed. */ if (kthread_is_per_cpu(p))
@@ -2408,6 +2413,10 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu) if (cpu_dying(cpu)) return false; + /* Non percpu kthreads should stay away from paravirt cpu*/ + if (cpu_paravirt(cpu)) + return false; + /* But are allowed during online. */ return cpu_online(cpu); }
--
2.47.3