Re: [PATCH v3 2/4] PM: hibernate: make direct map manipulations more explicit

[Kirill A. Shutemov]

On Tue, Nov 03, 2020 at 02:13:50PM +0200, Mike Rapoport wrote:
> On Tue, Nov 03, 2020 at 02:08:16PM +0300, Kirill A. Shutemov wrote:
> > On Sun, Nov 01, 2020 at 07:08:13PM +0200, Mike Rapoport wrote:
> > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> > > index 46b1804c1ddf..054c8cce4236 100644
> > > --- a/kernel/power/snapshot.c
> > > +++ b/kernel/power/snapshot.c
> > > @@ -76,6 +76,32 @@ static inline void hibernate_restore_protect_page(void *page_address) {}
> > >  static inline void hibernate_restore_unprotect_page(void *page_address) {}
> > >  #endif /* CONFIG_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */
> > >  
> > > +static inline void hibernate_map_page(struct page *page, int enable)
> > > +{
> > > +	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
> > > +		unsigned long addr = (unsigned long)page_address(page);
> > > +		int ret;
> > > +
> > > +		/*
> > > +		 * This should not fail because remapping a page here means
> > > +		 * that we only update protection bits in an existing PTE.
> > > +		 * It is still worth to have WARN_ON() here if something
> > > +		 * changes and this will no longer be the case.
> > > +		 */
> > > +		if (enable)
> > > +			ret = set_direct_map_default_noflush(page);
> > > +		else
> > > +			ret = set_direct_map_invalid_noflush(page);
> > > +
> > > +		if (WARN_ON(ret))
> > 
> > _ONCE?
> 
> I've changed it to pr_warn() after David said people enable panic on
> warn in production kernels.

pr_warn_once()? :P

-- 
 Kirill A. Shutemov