Re: [PATCH] ipc/shm.c add ->pagesize function to shm_vm_ops

[Jane Chu]

Hi, Mathew,


On 7/28/2018 12:02 PM, Matthew Wilcox wrote:
> On Fri, Jul 27, 2018 at 03:17:27PM -0600, Jane Chu wrote:
> > +++ b/include/linux/mm.h
> > @@ -387,6 +387,13 @@ enum page_entry_size {
> >    * These are the virtual MM functions - opening of an area, closing and
> >    * unmapping it (needed to keep files on disk up-to-date etc), pointer
> >    * to the functions called when a no-page or a wp-page exception occurs.
> > + *
> > + * Note, when a new function is introduced to vm_operations_struct and
> > + * added to hugetlb_vm_ops, please consider adding the function to
> > + * shm_vm_ops. This is because under System V memory model, though
> > + * mappings created via shmget/shmat with "huge page" specified are
> > + * backed by hugetlbfs files, their original vm_ops are overwritten with
> > + * shm_vm_ops.
> >    */
> >   struct vm_operations_struct {
> I don't think this header file is the right place for this comment.
> I'd think a better place for it would be at the definition of hugetlb_vm_ops.

Agreed, will make the change.
Thanks for reviewing!

-jane