From 3d680bdf60a5bade3e8cbd049927e7f8b1d3fe97 Mon Sep 17 00:00:00 2001 From: Qian Cai Date: Thu, 30 Jan 2020 22:15:01 -0800 Subject: [PATCH] mm/page_isolation: fix potential warning from user It makes sense to call the WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE) from start_isolate_page_range(), but should avoid triggering it from userspace, i.e, from is_mem_section_removable() because it could crash the system by a non-root user if warn_on_panic is set. While at it, simplify the code a bit by removing an unnecessary jump label. Link: http://lkml.kernel.org/r/20200120163915.1469-1-cai@lca.pw Signed-off-by: Qian Cai Suggested-by: Michal Hocko Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 11 ++++------- mm/page_isolation.c | 18 +++++++++++------- 2 files changed, 15 insertions(+), 14 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2a1a816c7992..15e908ad933b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8214,7 +8214,7 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, if (is_migrate_cma(migratetype)) return NULL; - goto unmovable; + return page; } for (; iter < pageblock_nr_pages; iter++) { @@ -8224,7 +8224,7 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, page = pfn_to_page(pfn + iter); if (PageReserved(page)) - goto unmovable; + return page; /* * If the zone is movable and we have ruled out all reserved @@ -8244,7 +8244,7 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, unsigned int skip_pages; if (!hugepage_migration_supported(page_hstate(head))) - goto unmovable; + return page; skip_pages = compound_nr(head) - (page - head); iter += skip_pages - 1; @@ -8286,12 +8286,9 @@ struct page *has_unmovable_pages(struct zone *zone, struct page *page, * is set to both of a memory hole page and a _used_ kernel * page at boot. */ - goto unmovable; + return page; } return NULL; -unmovable: - WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); - return pfn_to_page(pfn + iter); } #ifdef CONFIG_CONTIG_ALLOC diff --git a/mm/page_isolation.c b/mm/page_isolation.c index e70586523ca3..a9fd7c740c23 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -54,14 +54,18 @@ static int set_migratetype_isolate(struct page *page, int migratetype, int isol_ out: spin_unlock_irqrestore(&zone->lock, flags); - if (!ret) + if (!ret) { drain_all_pages(zone); - else if ((isol_flags & REPORT_FAILURE) && unmovable) - /* - * printk() with zone->lock held will guarantee to trigger a - * lockdep splat, so defer it here. - */ - dump_page(unmovable, "unmovable page"); + } else { + WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); + + if ((isol_flags & REPORT_FAILURE) && unmovable) + /* + * printk() with zone->lock held will likely trigger a + * lockdep splat, so defer it here. + */ + dump_page(unmovable, "unmovable page"); + } return ret; }