Commit 4a222127 authored Oct 26, 2018 by David Rientjes Committed by Linus Torvalds Oct 26, 2018

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: David Rientjes <rientjes@google.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus 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);

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