On 15.12.20 16:54, Liam R. Howlett wrote:
> do_mmap() will unlock the necessary VMAs. There is also a bug in the
> loop which will evaluate as false and not unlock any VMAs anyways.
If there is a BUG, do we have a Fixes: tag? Also
1. Can we fix the bug separately first?
2. Can we have a better description on what the bug actually is
"evaluate as false"? What is the result of the bug?
CCing some people that might know if this is actually a sane change.
Skimming over do_mmap(), it's not immediately clear to me that
"do_mmap() will unlock the necessary VMAs".
>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> ---
> mm/mmap.c | 18 +-----------------
> 1 file changed, 1 insertion(+), 17 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 5c8b4485860de..f7fecb77f84fd 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);
>
--
Thanks,
David / dhildenb
