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Subject[PATCH] mm: fix is_pinnable_page against on cma page
Date
Pages on CMA area could have MIGRATE_ISOLATE as well as MIGRATE_CMA
so current is_pinnable_page could miss CMA pages which has MIGRATE_
ISOLATE. It ends up putting CMA pages longterm pinning possible on
pin_user_pages APIs so CMA allocation fails.

The CMA allocation path protects the migration type change race
using zone->lock but what GUP path need to know is just whether the
page is on CMA area or not rather than exact type. Thus, we don't
need zone->lock but just checks the migratype in either of
(MIGRATE_ISOLATE and MIGRATE_CMA).

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
include/linux/mm.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6acca5cecbc5..f59bbe3296e3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1625,8 +1625,10 @@ static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
#ifdef CONFIG_MIGRATION
static inline bool is_pinnable_page(struct page *page)
{
- return !(is_zone_movable_page(page) || is_migrate_cma_page(page)) ||
- is_zero_pfn(page_to_pfn(page));
+ int mt = get_pageblock_migratetype(page);
+
+ return !(is_zone_movable_page(page) || mt == MIGRATE_CMA ||
+ mt == MIGRATE_ISOLATE || is_zero_pfn(page_to_pfn(page)));
}
#else
static inline bool is_pinnable_page(struct page *page)
--
2.36.0.464.gb9c8b46e94-goog
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