From: Deyan Wang <wonder_rock@xxxxxxx> Add a comment to explain why we call get_pfnblock_migratetype() twice in __free_pages_ok(). Signed-off-by: Deyan Wang <wonder_rock@xxxxxxx> --- mm/page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2d4c81224508..52dd4fff280b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1702,6 +1702,11 @@ static void __free_pages_ok(struct page *page, unsigned int order, if (!free_pages_prepare(page, order, true, fpi_flags)) return; + /* + * Calling get_pfnblock_migratetype() without spin_lock_irqsave() here + * is used to avoid calling get_pfnblock_migratetype() under the lock. + * This will reduce the lock holding time. + */ migratetype = get_pfnblock_migratetype(page, pfn); spin_lock_irqsave(&zone->lock, flags); -- 2.25.1
