[v11 PATCH 2/3] mm: unmap VM_HUGETLB mappings with optimized path

From: Yang Shi
Date: Wed Sep 19 2018 - 13:04:20 EST


When unmapping VM_HUGETLB mappings, vm flags need to be updated. Since
the vmas have been detached, so it sounds safe to update vm flags with
read mmap_sem.

Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 982dd00..490340e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2777,7 +2777,7 @@ static int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
* update vm_flags.
*/
if (downgrade &&
- (tmp->vm_flags & (VM_HUGETLB | VM_PFNMAP)))
+ (tmp->vm_flags & VM_PFNMAP))
downgrade = false;

tmp = tmp->vm_next;
--
1.8.3.1