2021-02-24 01:08:30

by Liam R. Howlett

Subject: [PATCH v3] mm/mmap: Don't unlock VMAs in remap_file_pages()

Since this call uses MAP_FIXED, do_mmap() will munlock the necessary
range. There is also an error in the loop test expression which will
evaluate as false and the loop body has never execute.

Signed-off-by: Liam R. Howlett <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
---
mm/mmap.c | 18 +-----------------
1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index dc7206032387c..e22b048733269 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3025,25 +3025,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,

flags &= MAP_NONBLOCK;
flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
- if (vma->vm_flags & VM_LOCKED) {
- struct vm_area_struct *tmp;
+ if (vma->vm_flags & VM_LOCKED)
flags |= MAP_LOCKED;

- /* drop PG_Mlocked flag for over-mapped range */
- for (tmp = vma; tmp->vm_start >= start + size;
- tmp = tmp->vm_next) {
- /*
- * Split pmd and munlock page on the border
- * of the range.
- */
- vma_adjust_trans_huge(tmp, start, start + size, 0);
-
- munlock_vma_pages_range(tmp,
- max(tmp->vm_start, start),
- min(tmp->vm_end, start + size));
- }
- }
-
file = get_file(vma->vm_file);
ret = do_mmap(vma->vm_file, start, size,
prot, flags, pgoff, &populate, NULL);
--
2.30.0

2021-02-24 07:14:22

by Matthew Wilcox

Subject: Re: [PATCH v3] mm/mmap: Don't unlock VMAs in remap_file_pages()

On Tue, Feb 23, 2021 at 11:50:23PM +0000, Liam Howlett wrote:
> Since this call uses MAP_FIXED, do_mmap() will munlock the necessary
> range. There is also an error in the loop test expression which will
> evaluate as false and the loop body has never execute.
>
> Signed-off-by: Liam R. Howlett <[email protected]>
> Acked-by: Hugh Dickins <[email protected]>

Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>

2021-02-24 10:19:16

by David Hildenbrand

Subject: Re: [PATCH v3] mm/mmap: Don't unlock VMAs in remap_file_pages()

On 24.02.21 00:50, Liam Howlett wrote:
> Since this call uses MAP_FIXED, do_mmap() will munlock the necessary
> range. There is also an error in the loop test expression which will
> evaluate as false and the loop body has never execute.
>
> Signed-off-by: Liam R. Howlett <[email protected]>
> Acked-by: Hugh Dickins <[email protected]>
> ---
> mm/mmap.c | 18 +-----------------
> 1 file changed, 1 insertion(+), 17 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index dc7206032387c..e22b048733269 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3025,25 +3025,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
>
> flags &= MAP_NONBLOCK;
> flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
> - if (vma->vm_flags & VM_LOCKED) {
> - struct vm_area_struct *tmp;
> + if (vma->vm_flags & VM_LOCKED)
> flags |= MAP_LOCKED;
>
> - /* drop PG_Mlocked flag for over-mapped range */
> - for (tmp = vma; tmp->vm_start >= start + size;
> - tmp = tmp->vm_next) {
> - /*
> - * Split pmd and munlock page on the border
> - * of the range.
> - */
> - vma_adjust_trans_huge(tmp, start, start + size, 0);
> -
> - munlock_vma_pages_range(tmp,
> - max(tmp->vm_start, start),
> - min(tmp->vm_end, start + size));
> - }
> - }
> -
> file = get_file(vma->vm_file);
> ret = do_mmap(vma->vm_file, start, size,
> prot, flags, pgoff, &populate, NULL);
>

Reviewed-by: David Hildenbrand <[email protected]>

--
Thanks,

David / dhildenb