On 08/03/2017 05:11 PM, Michal Hocko wrote:
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?
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.
struct free_area *free_area = &zone->free_area[order];
enum migratetype mt;
struct page *page;
if (!free_area->nr_pages)
continue;
for_each_migratetype_order(order, mt) {
list_for_each_entry(page,
&free_area->free_list[mt], lru) {
pfn = page_to_pfn(page);
visit(opaque2, prn, 1<<order);
}
}
}
spin_unlock_irqrestore(&zone->lock, flags);
}
[...]
What do you think if we further simply the above implementation like this:
for_each_populated_zone(zone) {
for_each_migratetype_order_decend(1, order, mt) {
spin_lock_irqsave(&zone->lock, flags);
list_for_each_entry(page,
&zone->free_area[order].free_list[mt], lru) {
pfn = page_to_pfn(page);
visit(opaque1, pfn, 1 << order);
}
spin_unlock_irqrestore(&zone->lock, flags);
}
}
Best,
Wei
