[RFC v10 PATCH 2/3] mm: unmap VM_HUGETLB mappings with optimized path

[Yang Shi]

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 <mho...@kernel.org>
Cc: Vlastimil Babka <vba...@suse.cz>
Signed-off-by: Yang Shi <yang....@linux.alibaba.com>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 2879b19..991e066 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