On Sun, Aug 23, 2026 at 03:17:38PM +0300, Mike Rapoport (Microsoft) wrote: > gup_can_follow_protnone() is defined in include/linux/mm.h but only used > by mm/gup.c. > > First, there is no reason to have it in already gigantic header. > > Next, the upcoming refactoring of userfaultfd flags will make > gup_can_follow_protnone() depend on userfaultfd_k.h which would cause a > cyclic header dependency. > > Move gup_can_follow_protnone() to mm/gup.c. > > No functional change. > > Assisted-by: copilot:claude-opus-5 > Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) <[email protected]> > --- > include/linux/mm.h | 38 -------------------------------------- > mm/gup.c | 38 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+), 38 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 0829e0d3b2d1..4daf9cd6ae8e 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -4860,44 +4860,6 @@ static inline int vm_fault_to_errno(vm_fault_t > vm_fault, int foll_flags) > return 0; > } > > -/* > - * Indicates whether GUP can follow a PROT_NONE mapped page, or whether > - * a (NUMA hinting or userfaultfd RWP) fault is required. > - */ > -static inline bool gup_can_follow_protnone(const struct vm_area_struct *vma, > - unsigned int flags) > -{ > - /* > - * VM_UFFD_RWP uses protnone as an access-tracking marker, not for > - * NUMA hinting. GUP must always take a fault so the access is > - * delivered to userfaultfd, regardless of FOLL_HONOR_NUMA_FAULT. > - * > - * Only do so while the VMA is accessible. If it has been made > - * inaccessible (e.g. mprotect(PROT_NONE)), fall through to the guard > - * below: forcing a fault there would loop, as handle_mm_fault() makes > - * no progress on protnone in an inaccessible VMA, and the access is > - * denied regardless of RWP anyway. > - */ > - if (vma_test_single_mask(vma, VMA_UFFD_RWP) && vma_is_accessible(vma)) > - return false; > - > - /* > - * If callers don't want to honor NUMA hinting faults, no need to > - * determine if we would actually have to trigger a NUMA hinting fault. > - */ > - if (!(flags & FOLL_HONOR_NUMA_FAULT)) > - return true; > - > - /* > - * NUMA hinting faults don't apply in inaccessible (PROT_NONE) VMAs. > - * > - * Requiring a fault here even for inaccessible VMAs would mean that > - * FOLL_FORCE cannot make any progress, because handle_mm_fault() > - * refuses to process NUMA hinting faults in inaccessible VMAs. > - */ > - return !vma_is_accessible(vma); > -} > - > typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data); > extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, > unsigned long size, pte_fn_t fn, void *data); > diff --git a/mm/gup.c b/mm/gup.c > index eb898ea1ee22..500e2aa99e48 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -633,6 +633,44 @@ static struct page *no_page_table(struct vm_area_struct > *vma, > return NULL; > } > > +/* > + * Indicates whether GUP can follow a PROT_NONE mapped page, or whether > + * a (NUMA hinting or userfaultfd RWP) fault is required. > + */ > +static inline bool gup_can_follow_protnone(const struct vm_area_struct *vma, > + unsigned int flags) > +{ > + /* > + * VM_UFFD_RWP uses protnone as an access-tracking marker, not for > + * NUMA hinting. GUP must always take a fault so the access is > + * delivered to userfaultfd, regardless of FOLL_HONOR_NUMA_FAULT. > + * > + * Only do so while the VMA is accessible. If it has been made > + * inaccessible (e.g. mprotect(PROT_NONE)), fall through to the guard > + * below: forcing a fault there would loop, as handle_mm_fault() makes > + * no progress on protnone in an inaccessible VMA, and the access is > + * denied regardless of RWP anyway. > + */ > + if (vma_test_single_mask(vma, VMA_UFFD_RWP) && vma_is_accessible(vma)) > + return false; > + > + /* > + * If callers don't want to honor NUMA hinting faults, no need to > + * determine if we would actually have to trigger a NUMA hinting fault. > + */ > + if (!(flags & FOLL_HONOR_NUMA_FAULT)) > + return true; > + > + /* > + * NUMA hinting faults don't apply in inaccessible (PROT_NONE) VMAs. > + * > + * Requiring a fault here even for inaccessible VMAs would mean that > + * FOLL_FORCE cannot make any progress, because handle_mm_fault() > + * refuses to process NUMA hinting faults in inaccessible VMAs. > + */ > + return !vma_is_accessible(vma); > +} > + > #ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES > /* FOLL_FORCE can write to even unwritable PUDs in COW mappings. */ > static inline bool can_follow_write_pud(pud_t pud, struct page *page, > > -- > 2.53.0 > -- Cheers, Lorenzo
