On Mon 01-12-14 17:58:01, Johannes Weiner wrote:
> The only way a VMA can have shared and writable semantics is with a
> backing file.
OK, one always learns :) After some digging I found that MAP_SHARED |
MAP_ANONYMOUS mappings are in fact mappings of a temporary file in tmpfs.
It would be worth to mention this in the changelog I believe. Otherwise
feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
>
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
> mm/memory.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 73220eb6e9e3..2a2e3648ed65 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2167,9 +2167,7 @@ reuse:
> balance_dirty_pages_ratelimited(mapping);
> }
>
> - /* file_update_time outside page_lock */
> - if (vma->vm_file)
> - file_update_time(vma->vm_file);
> + file_update_time(vma->vm_file);
> }
> put_page(dirty_page);
> if (page_mkwrite) {
> @@ -3025,8 +3023,7 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
> balance_dirty_pages_ratelimited(mapping);
> }
>
> - /* file_update_time outside page_lock */
> - if (vma->vm_file && !vma->vm_ops->page_mkwrite)
> + if (!vma->vm_ops->page_mkwrite)
> file_update_time(vma->vm_file);
>
> return ret;
> --
> 2.1.3
>
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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