Commit ac4b2901 authored by Deyan Wang's avatar Deyan Wang Committed by Andrew Morton
Browse files

mm/page_alloc: update comments in __free_pages_ok() 

Add a comment to explain why we call get_pfnblock_migratetype() twice in
__free_pages_ok().

Link: https://lkml.kernel.org/r/20221201135045.31663-1-wonder_rock@126.com


Signed-off-by: default avatarDeyan Wang <wonder_rock@126.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 48001795

mm/page_alloc.c

+5 −0
Original line number Diff line number Diff line
@@ -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);