Re: [PATCH 18/30] x86, kaiser: map virtually-addressed performance monitoring buffers

[Dave Hansen]

On 11/14/2017 10:20 AM, Peter Zijlstra wrote:
> On Fri, Nov 10, 2017 at 11:31:39AM -0800, Dave Hansen wrote:
>>  static int alloc_ds_buffer(int cpu)
>>  {
>> +	struct debug_store *ds = per_cpu_ptr(&cpu_debug_store, cpu);
>>  
>> +	memset(ds, 0, sizeof(*ds));
> Still wondering about that memset...

My guess is that it was done to mirror the zeroing done by the original
kzalloc().  But, I think you're right that it's zero'd already by virtue
of being static:

static
DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct debug_store,
cpu_debug_store);

I'll queue a cleanup, or update it if I re-post the set.