__free_pages_ok() disables IRQs before calling a common helper
free_one_page() that acquires the zone lock. While this is safe, it
unnecessarily disables IRQs on PREEMPT_RT kernels.
This patch explicitly acquires the lock with spin_lock_irqsave instead of
relying on a helper. This removes the last instance of local_irq_save()
in page_alloc.c.
Signed-off-by: Mel Gorman <[email protected]>
---
mm/page_alloc.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1bb5b522a0f9..d94ec53367bd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1559,21 +1559,18 @@ static void __free_pages_ok(struct page *page, unsigned int order,
unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
+ struct zone *zone = page_zone(page);
if (!free_pages_prepare(page, order, true))
return;
migratetype = get_pfnblock_migratetype(page, pfn);
- /*
- * TODO FIX: Disable IRQs before acquiring IRQ-safe zone->lock
- * and protect vmstat updates.
- */
- local_irq_save(flags);
+ spin_lock_irqsave(&zone->lock, flags);
__count_vm_events(PGFREE, 1 << order);
- free_one_page(page_zone(page), page, pfn, order, migratetype,
- fpi_flags);
- local_irq_restore(flags);
+ migratetype = check_migratetype_isolated(zone, page, pfn, migratetype);
+ __free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
+ spin_unlock_irqrestore(&zone->lock, flags);
}
void __free_pages_core(struct page *page, unsigned int order)
--
2.26.2