Re: [RFC V2 4/6] sh/mm: Stop using [p4d|pud|pmd]_ERROR()

On Wed, Aug 12, 2026 at 01:21:28PM +0200, David Hildenbrand (Arm) wrote:
> On 8/11/26 06:21, Anshuman Khandual wrote:
> > Stop using [p4d|pud|pmd]_ERROR() in __get_pte_phys() as the pgtable entries
> > are known to be NULL and hence could not really be accessed.
> > 
> > Cc: Yoshinori Sato <[email protected]>
> > Cc: Rich Felker <[email protected]>
> > Cc: John Paul Adrian Glaubitz <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Signed-off-by: Anshuman Khandual <[email protected]>
> > ---
> >  arch/sh/mm/init.c | 12 +++---------
> >  1 file changed, 3 insertions(+), 9 deletions(-)
> > 
> > diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
> > index b3c7fd84ceb4..0bb8555568a4 100644
> > --- a/arch/sh/mm/init.c
> > +++ b/arch/sh/mm/init.c
> > @@ -58,22 +58,16 @@ static pte_t *__get_pte_phys(unsigned long addr)
> >  	}
> >  
> >  	p4d = p4d_alloc(NULL, pgd, addr);
> > -	if (unlikely(!p4d)) {
> > -		p4d_ERROR(*p4d);
> > +	if (unlikely(!p4d))
> >  		return NULL;
> > -	}
> >  
> >  	pud = pud_alloc(NULL, p4d, addr);
> > -	if (unlikely(!pud)) {
> > -		pud_ERROR(*pud);
> > +	if (unlikely(!pud))
> >  		return NULL;
> > -	}
> >  
> >  	pmd = pmd_alloc(NULL, pud, addr);
> > -	if (unlikely(!pmd)) {
> > -		pmd_ERROR(*pmd);
> > +	if (unlikely(!pmd))
> >  		return NULL;
> > -	}
> >  
> >  	return pte_offset_kernel(pmd, addr);
> >  }
> 
> Do we want to print an error like "allocating p4d table failed"?

Sure, will add error prints like the following.

--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -56,16 +56,22 @@ static pte_t *__get_pte_phys(unsigned long addr)
                return NULL;

        p4d = p4d_alloc(NULL, pgd, addr);
-       if (unlikely(!p4d))
+       if (unlikely(!p4d)) {
+               pr_err("allocating p4d table failed\n");
                return NULL;
+       }

        pud = pud_alloc(NULL, p4d, addr);
-       if (unlikely(!pud))
+       if (unlikely(!pud)) {
+               pr_err("allocating pud table failed\n");
                return NULL;
+       }

        pmd = pmd_alloc(NULL, pud, addr);
-       if (unlikely(!pmd))
+       if (unlikely(!pmd)) {
+               pr_err("allocating pmd table failed\n");
                return NULL;
+       }

        return pte_offset_kernel(pmd, addr);
 }

> 
> Reviewed-by: David Hildenbrand (Arm) <[email protected]>
> 
> -- 
> Cheers,
> 
> David