Commit 822fc613 authored Apr 15, 2015 by Naoya Horiguchi Committed by Linus Torvalds Apr 15, 2015

mm: don't call __page_cache_release for hugetlb



__put_compound_page() calls __page_cache_release() to do some freeing
work, but it's obviously for thps, not for hugetlb.  We don't care because
PageLRU is always cleared and page->mem_cgroup is always NULL for hugetlb.
But it's not correct and has potential risks, so let's make it
conditional.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 9fcd1457

mm/swap.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -31,6 +31,7 @@
		#include <linux/memcontrol.h>
		#include <linux/gfp.h>
		#include <linux/uio.h>
		#include <linux/hugetlb.h>

		#include "internal.h"

		@@ -75,6 +76,13 @@ static void __put_compound_page(struct page *page)
		{
		compound_page_dtor *dtor;

		/*
		* __page_cache_release() is supposed to be called for thp, not for
		* hugetlb. This is because hugetlb page does never have PageLRU set
		* (it's never listed to any LRU lists) and no memcg routines should
		* be called for hugetlb (it has a separate hugetlb_cgroup.)
		*/
		if (!PageHuge(page))
		__page_cache_release(page);
		dtor = get_compound_page_dtor(page);
		(*dtor)(page);