On Tue, Dec 18, 2018 at 12:31:19PM +0100, Peter Zijlstra wrote:
> On Tue, Dec 18, 2018 at 12:16:37PM +0100, Sebastian Andrzej Siewior wrote:
> > On 2018-12-18 12:02:09 [+0100], Peter Zijlstra wrote:
> > > On Tue, Dec 18, 2018 at 06:30:33PM +0800, zhe.he@xxxxxxxxxxxxx wrote:
> > > > Besides, in preempt-rt full mode, the freeing can happen in atomic context and
> > > > thus cause the following BUG.
> > >
> > > Hurm, I though we fixed all those long ago..
> > >
> > > And no, the patch is horrible; that's what we have things like
> > > x86_pmu::cpu_dead() for.
> >
> > ehm, you say we keep memory allocation +free on CPU up/down?
>
> Sure, why not?
I suspect the below is all we really need.
---
arch/x86/events/intel/core.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 40e12cfc87f6..daafb893449b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3558,6 +3558,14 @@ static void free_excl_cntrs(int cpu)
}
static void intel_pmu_cpu_dying(int cpu)
+{
+ fini_debug_store_on_cpu(cpu);
+
+ if (x86_pmu.counter_freezing)
+ disable_counter_freeze();
+}
+
+static void intel_pmu_cpu_dead(int cpu)
{
struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
struct intel_shared_regs *pc;
@@ -3570,11 +3578,6 @@ static void intel_pmu_cpu_dying(int cpu)
}
free_excl_cntrs(cpu);
-
- fini_debug_store_on_cpu(cpu);
-
- if (x86_pmu.counter_freezing)
- disable_counter_freeze();
}
static void intel_pmu_sched_task(struct perf_event_context *ctx,
@@ -3663,6 +3666,7 @@ static __initconst const struct x86_pmu core_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
};
static struct attribute *intel_pmu_attrs[];
@@ -3703,6 +3707,8 @@ static __initconst const struct x86_pmu intel_pmu = {
.cpu_prepare = intel_pmu_cpu_prepare,
.cpu_starting = intel_pmu_cpu_starting,
.cpu_dying = intel_pmu_cpu_dying,
+ .cpu_dead = intel_pmu_cpu_dead,
+
.guest_get_msrs = intel_guest_get_msrs,
.sched_task = intel_pmu_sched_task,
};
