From 6a654e36fa51a4ae1f109b0b30a23d3f097b3d8a Mon Sep 17 00:00:00 2001 From: Li Xinhai Date: Tue, 13 Oct 2020 16:55:39 -0700 Subject: mm, isolation: avoid checking unmovable pages across pageblock boundary In has_unmovable_pages(), the page parameter would not always be the first page within a pageblock (see how the page pointer is passed in from start_isolate_page_range() after call __first_valid_page()), so that would cause checking unmovable pages span two pageblocks. After this patch, the checking is enforced within one pageblock no matter the page is first one or not, and obey the semantics of this function. This issue is found by code inspection. Michal said "this might lead to false negatives when an unrelated block would cause an isolation failure". Signed-off-by: Li Xinhai Signed-off-by: Andrew Morton Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: David Hildenbrand Link: https://lkml.kernel.org/r/20200824065811.383266-1-lixinhai.lxh@gmail.com Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ff0b14b0e8d7..b9f9b51e0342 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8234,6 +8234,7 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, { unsigned long iter = 0; unsigned long pfn = page_to_pfn(page); + unsigned long offset = pfn % pageblock_nr_pages; if (is_migrate_cma_page(page)) { /* @@ -8247,7 +8248,7 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, return page; } - for (; iter < pageblock_nr_pages; iter++) { + for (; iter < pageblock_nr_pages - offset; iter++) { if (!pfn_valid_within(pfn + iter)) continue; -- cgit v1.2.3