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

[Jason Gunthorpe]

On Fri, Jun 12, 2020 at 12:53:23PM -0700, Ralph Campbell wrote:
> 
> 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.

Yes, that is clearer to me

Jason