diff options
| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2020-10-20 09:47:14 -0400 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-10-29 11:00:31 +0100 |
| commit | 618758ed3a4f7d790414d020b362111748ebbf9f (patch) | |
| tree | 9357b04f04a5ef25a162bed531eedce691339280 /kernel/sched/membarrier.c | |
| parent | 5bc78502322a5e4eef3f1b2a2813751dc6434143 (diff) | |
sched: membarrier: cover kthread_use_mm (v4)
Add comments and memory barrier to kthread_use_mm and kthread_unuse_mm
to allow the effect of membarrier(2) to apply to kthreads accessing
user-space memory as well.
Given that no prior kthread use this guarantee and that it only affects
kthreads, adding this guarantee does not affect user-space ABI.
Refine the check in membarrier_global_expedited to exclude runqueues
running the idle thread rather than all kthreads from the IPI cpumask.
Now that membarrier_global_expedited can IPI kthreads, the scheduler
also needs to update the runqueue's membarrier_state when entering lazy
TLB state.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201020134715.13909-3-mathieu.desnoyers@efficios.com
Diffstat (limited to 'kernel/sched/membarrier.c')
| -rw-r--r-- | kernel/sched/membarrier.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index aac329258af0..f223f3590b8f 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -126,12 +126,11 @@ static int membarrier_global_expedited(void) continue; /* - * Skip the CPU if it runs a kernel thread. The scheduler - * leaves the prior task mm in place as an optimization when - * scheduling a kthread. + * Skip the CPU if it runs a kernel thread which is not using + * a task mm. */ p = rcu_dereference(cpu_rq(cpu)->curr); - if (p->flags & PF_KTHREAD) + if (!p->mm) continue; __cpumask_set_cpu(cpu, tmpmask); |