diff mbox series

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

Message ID 1536957299-43536-3-git-send-email-yang.shi@linux.alibaba.com (mailing list archive)
State New, archived
Headers show
Series mm: zap pages with read mmap_sem in munmap for large mapping | expand

Commit Message

Yang Shi Sept. 14, 2018, 8:34 p.m. UTC 
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@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
 mm/mmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Matthew Wilcox (Oracle) Sept. 15, 2018, 9:44 a.m. UTC | #1 
On Sat, Sep 15, 2018 at 04:34:58AM +0800, Yang Shi wrote:
> 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@kernel.org>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>

Reviewed-by: Matthew Wilcox <willy@infradead.org>
diff mbox series

Patch

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;