Re: [PATCH 11/19] mm: page_alloc: Lookup pageblock migratetype with IRQs enabled during free

From: Vlastimil Babka
Date: Tue May 13 2014 - 09:36:31 EST


On 05/13/2014 11:45 AM, Mel Gorman wrote:
get_pageblock_migratetype() is called during free with IRQs disabled. This
is unnecessary and disables IRQs for longer than necessary.

Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>

With a comment below,

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

---
mm/page_alloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3948f0a..fcbf637 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -773,9 +773,9 @@ static void __free_pages_ok(struct page *page, unsigned int order)
if (!free_pages_prepare(page, order))
return;

+ migratetype = get_pfnblock_migratetype(page, pfn);
local_irq_save(flags);
__count_vm_events(PGFREE, 1 << order);
- migratetype = get_pfnblock_migratetype(page, pfn);
set_freepage_migratetype(page, migratetype);

The line above could be also outside disabled IRQ, no?

free_one_page(page_zone(page), page, pfn, order, migratetype);
local_irq_restore(flags);


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