On Fri, Mar 4, 2022 at 12:32 AM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>
>
> Ah, you found out already. Well maybe it could simply be moved inside the
> loop under the locked section and always done when page != NULL? I mean if
> check_new_pages() fails we just leak the problematic pages anyway so they
> are no longer free to allocate anymore and we should not count them as such.
>
Yes, and I guess that calling __mod_zone_freepage_state() for the page
about to be leaked
is just fine.
This means we can call check_newpages() without holding zone spinlock
or hard irqs being masked.
I will test something like:
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3589febc6d31928f850ebe5a4015ddc40e0469f3..1804287c1b792b8aa0e964b17eb002b6b1115258
100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3706,10 +3706,10 @@ struct page *rmqueue(struct zone *preferred_zone,
* allocate greater than order-1 page units with __GFP_NOFAIL.
*/
WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
- spin_lock_irqsave(&zone->lock, flags);
do {
page = NULL;
+ spin_lock_irqsave(&zone->lock, flags);
/*
* order-0 request can reach here when the pcplist is skipped
* due to non-CMA allocation context. HIGHATOMIC area is
@@ -3721,15 +3721,15 @@ struct page *rmqueue(struct zone *preferred_zone,
if (page)
trace_mm_page_alloc_zone_locked(page,
order, migratetype);
}
- if (!page)
+ if (!page) {
page = __rmqueue(zone, order, migratetype, alloc_flags);
- } while (page && check_new_pages(page, order));
- if (!page)
- goto failed;
-
- __mod_zone_freepage_state(zone, -(1 << order),
- get_pcppage_migratetype(page));
- spin_unlock_irqrestore(&zone->lock, flags);
+ if (!page)
+ goto failed;
+ }
+ __mod_zone_freepage_state(zone, -(1 << order),
+ get_pcppage_migratetype(page));
+ spin_unlock_irqrestore(&zone->lock, flags);
+ } while (check_new_pages(page, order));
__count_zid_vm_events(PGALLOC, page_zonenum(page), 1 << order);
zone_statistics(preferred_zone, zone, 1);
