Re: [PATCH v2] mm: Introduce new function vm_insert_kmem_page

[Souptick Joarder]

On Fri, Oct 5, 2018 at 1:16 AM Miguel Ojeda
<miguel.ojeda.sandonis@xxxxxxxxx> wrote:
>
> Hi Souptick,
>
> On Thu, Oct 4, 2018 at 8:49 PM Souptick Joarder <jrdr.linux@xxxxxxxxx> wrote:
> >
> > On Thu, Oct 4, 2018 at 11:47 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> > >
> > > I think this is a bad plan.  What we should rather do is examine the current
> > > users of vm_insert_page() and ask "What interface would better replace
> > > vm_insert_page()?"
> > >
> > > As I've said to you before, I believe the right answer is to have a
> > > vm_insert_range() which takes an array of struct page pointers.  That
> > > fits the majority of remaining users.
> >
> > Ok, but it will take some time.
> > Is it a good idea to introduce the final vm_fault_t patch and then
> > start working on vm_insert_range as it will be bit time consuming ?
> >
>
> Well, why is there a rush? Development should be done in a patch
> series or a tree, and submitted as a whole, instead of sending partial
> patches.

Not in hurry, will do it in a patch series :-)
>
> Also, not sure if you saw my comments/review: if the interface is not
> going to change, why the name change? Why can't we simply keep using
> vm_insert_page?

yes, changing the name without changing the interface is a
bad approach and this can't be taken. As Matthew mentioned,
"vm_insert_range() which takes an array of struct page pointers.
That fits the majority of remaining users" would be a better approach
to fit this use case.

But yes, we can't keep vm_insert_page and vmf_insert_page together
as it doesn't guarantee  that future drivers will not use vm_insert_page
in #PF context ( which will generate new errno to VM_FAULT_CODE).

Any further comment form others on vm_Insert_range() approach ?