If __isolate_free_page() failed, due to zone watermark check, the page is still on the free list. But this page will be put back to free list again via __putback_isolated_page() now. This may trigger page->flags checks in __free_one_page() if PageReported is set. Or we will corrupt the free list because list_add() will be called for pages already on another list. Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> --- v1->v2: Add VM_WARN_ON to catch unexpected isolating failure. --- mm/page_isolation.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/page_isolation.c b/mm/page_isolation.c index f93cc63d8fa1..f67c4c70f17f 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -94,8 +94,13 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) buddy = page + (buddy_pfn - pfn); if (!is_migrate_isolate_page(buddy)) { - __isolate_free_page(page, order); - isolated_page = true; + isolated_page = !!__isolate_free_page(page, order); + /* + * Isolating a free page in an isolated pageblock + * is expected to always work as watermarks don't + * apply here. + */ + VM_WARN_ON(!isolated_page); } } } -- 2.23.0