From: David Rientjes <rientjes@xxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Greg Thelen <gthelen@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-set-num_movable-in-move_freepages +++ a/mm/page_alloc.c @@ -2021,10 +2021,6 @@ static int move_freepages(struct zone *z 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 *zo 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); _
