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

[Jason Gunthorpe]

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