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Commit 4a222127 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm/page_alloc.c: initialize num_movable in move_freepages() 

If move_freepages_block() returns 0 because !zone_spans_pfn(),
*num_movable can hold the value from the stack because it does not get
initialized in move_freepages().

Move the initialization to move_freepages_block() to guarantee the value
actually makes sense.

This currently doesn't affect its only caller where num_movable != NULL,
so no bug fix, but just more robust.

Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1810051355490.212229@chino.kir.corp.google.com


Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 61855f02

mm/page_alloc.c

+3 −4
Original line number Diff line number Diff line
@@ -2021,10 +2021,6 @@ static int move_freepages(struct zone *zone, 
	          pfn_valid(page_to_pfn(end_page)) &&

	          page_zone(start_page) != page_zone(end_page));

#endif



	if (num_movable)

		*num_movable = 0;



	for (page = start_page; page <= end_page;) {

		if (!pfn_valid_within(page_to_pfn(page))) {

			page++;
@@ -2064,6 +2060,9 @@ int move_freepages_block(struct zone *zone, struct page *page, 
	unsigned long start_pfn, end_pfn;

	struct page *start_page, *end_page;



	if (num_movable)

		*num_movable = 0;



	start_pfn = page_to_pfn(page);

	start_pfn = start_pfn & ~(pageblock_nr_pages-1);

	start_page = pfn_to_page(start_pfn);