Re: [virtio-dev] Re: [PATCH v13 4/5] mm: support reporting free page blocks

On Tue 08-08-17 14:34:25, Wei Wang wrote:

On 08/08/2017 02:12 PM, Wei Wang wrote:

quoted

On 08/03/2017 05:11 PM, Michal Hocko wrote:

quoted

On Thu 03-08-17 14:38:18, Wei Wang wrote:
This is just too ugly and wrong actually. Never provide struct page
pointers outside of the zone->lock. What I've had in mind was to simply
walk free lists of the suitable order and call the callback for each
one.
Something as simple as

   for (i = 0; i < MAX_NR_ZONES; i++) {
       struct zone *zone = &pgdat->node_zones[i];

       if (!populated_zone(zone))
           continue;

Can we directly use for_each_populated_zone(zone) here?

yes, my example couldn't because I was still assuming per-node API

quoted

quoted

spin_lock_irqsave(&zone->lock, flags);
       for (order = min_order; order < MAX_ORDER; ++order) {

This appears to be covered by for_each_migratetype_order(order, mt) below.

yes but
#define for_each_migratetype_order(order, type) \
	for (order = 0; order < MAX_ORDER; order++) \
		for (type = 0; type < MIGRATE_TYPES; type++)

so you would have to skip orders < min_order
-- 
Michal Hocko
SUSE Labs