[PATCH v8 08/19] sched: Reject CPU affinity changes based on task_cpu_possible_mask()
From: Will Deacon <will@kernel.org>
Date: 2021-06-02 16:48:09
Also in:
linux-arm-kernel, lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
Reject explicit requests to change the affinity mask of a task via set_cpus_allowed_ptr() if the requested mask is not a subset of the mask returned by task_cpu_possible_mask(). This ensures that the 'cpus_mask' for a given task cannot contain CPUs which are incapable of executing it, except in cases where the affinity is forced. Reviewed-by: Quentin Perret <redacted> Signed-off-by: Will Deacon <will@kernel.org> --- kernel/sched/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0c1b6f1a6c91..b23c7f0ab31a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -2347,15 +2347,17 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, u32 flags) { const struct cpumask *cpu_valid_mask = cpu_active_mask; + const struct cpumask *cpu_allowed_mask = task_cpu_possible_mask(p); unsigned int dest_cpu; struct rq_flags rf; struct rq *rq; int ret = 0; + bool kthread = p->flags & PF_KTHREAD; rq = task_rq_lock(p, &rf); update_rq_clock(rq); - if (p->flags & PF_KTHREAD || is_migration_disabled(p)) { + if (kthread || is_migration_disabled(p)) { /* * Kernel threads are allowed on online && !active CPUs, * however, during cpu-hot-unplug, even these might get pushed
@@ -2369,6 +2371,11 @@ static int __set_cpus_allowed_ptr(struct task_struct *p, cpu_valid_mask = cpu_online_mask; } + if (!kthread && !cpumask_subset(new_mask, cpu_allowed_mask)) { + ret = -EINVAL; + goto out; + } + /* * Must re-check here, to close a race against __kthread_bind(), * sched_setaffinity() is not guaranteed to observe the flag.
--
2.32.0.rc0.204.g9fa02ecfa5-goog