Re: [PATCH] mm/hmm: remove redundant check non_swap_entry()

[Ralph Campbell]

On 6/12/20 12:42 PM, Jason Gunthorpe wrote:
> On Fri, Jun 12, 2020 at 12:35:24PM -0700, Matthew Wilcox wrote:
> > On Fri, Jun 12, 2020 at 12:26:18PM -0700, Ralph Campbell wrote:
> > > In zap_pte_range(), the check for non_swap_entry() and
> > > is_device_private_entry() is redundant since the latter is a subset of the
> > > former. Remove the redundant check to simplify the code and for clarity.
> >
> > That is highly configuration dependent.
> >
> > #else /* CONFIG_DEVICE_PRIVATE */
> > ...
> > static inline bool is_device_private_entry(swp_entry_t entry)
> > {
> >          return false;
> > }
>
> The commit message might be a bit confusing, as it is not a subset, I
> would say that device_private_entry alone is sufficient to tell if the
> entry is private or not.
>
> For the !CONFIG_DEVICE_PRIVATE case having it wired to false is
> right.
>
> Jason

How about the following message instead?

In zap_pte_range(), the check for non_swap_entry() and
is_device_private_entry() is unnecessary since the latter is sufficient
to determine if the page is a device private page. Remove the test for
non_swap_entry() to simplify the code and for clarity.