As for FOLL_LONGTERM, it is checked in the slow path
__gup_longterm_unlocked(). But it is not checked in the fast path, which
means a possible leak of CMA page to longterm pinned requirement through
this crack.
Place a check in the fast path.
Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
mm/gup.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c
index f173fcb..00feab3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2235,6 +2235,18 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
local_irq_enable();
ret = nr;
}
+#if defined(CONFIG_CMA)
+ if (unlikely(gup_flags & FOLL_LONGTERM)) {
+ int i, j;
+
+ for (i = 0; i < nr; i++)
+ if (is_migrate_cma_page(pages[i])) {
+ for (j = i; j < nr; j++)
+ put_page(pages[j]);
+ nr = i;
+ }
+ }
+#endif
if (nr < nr_pages) {
/* Try to get the remaining pages with get_user_pages */
--
2.7.5
