Re: [PATCH v7 01/12] khugepaged: rename hpage_collapse_* to khugepaged_*

[Nico Pache <npache@redhat.com>]

On Fri, May 16, 2025 at 11:36 AM Liam R. Howlett
<Liam.Howlett@oracle.com> wrote:
>
> * Nico Pache <npache@redhat.com> [250514 23:23]:
> > functions in khugepaged.c use a mix of hpage_collapse and khugepaged
> > as the function prefix.
> >
> > rename all of them to khugepaged to keep things consistent and slightly
> > shorten the function names.
>
> I don't like what was done here, we've lost the context of what these
> functions are used for (collapse). Are they used for other things
> besides collapse?
Hi Liam,

Most of the renamed functions are used by the daemon to determine the
state of the khugepaged operations. You could argue that
madvise_collapse is not part of the daemon, and a couple of them are
both khugepaged and madvise_collapse, but what I do in the subsequent
patch is *mostly* unify madvise_collapse and khugepaged.

I personally believe this rename makes sense (and it was recommended
by David H.)



-- Nico

>
> I'd rather drop the prefix entirely than drop collapse from them all.
> They are all static, so do we really need khugepaged_ at the start of
> every static function in khugepaged.c?
>
>
> >
> > Reviewed-by: Zi Yan <ziy@nvidia.com>
> > Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> > Signed-off-by: Nico Pache <npache@redhat.com>
> > ---
> >  mm/khugepaged.c | 42 +++++++++++++++++++++---------------------
> >  1 file changed, 21 insertions(+), 21 deletions(-)
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index cdf5a581368b..806bcd8c5185 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -402,14 +402,14 @@ void __init khugepaged_destroy(void)
> >       kmem_cache_destroy(mm_slot_cache);
> >  }
> >
> > -static inline int hpage_collapse_test_exit(struct mm_struct *mm)
> > +static inline int khugepaged_test_exit(struct mm_struct *mm)
> >  {
> >       return atomic_read(&mm->mm_users) == 0;
> >  }
> >
> > -static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *mm)
> > +static inline int khugepaged_test_exit_or_disable(struct mm_struct *mm)
> >  {
> > -     return hpage_collapse_test_exit(mm) ||
> > +     return khugepaged_test_exit(mm) ||
> >              test_bit(MMF_DISABLE_THP, &mm->flags);
> >  }
> >
> > @@ -444,7 +444,7 @@ void __khugepaged_enter(struct mm_struct *mm)
> >       int wakeup;
> >
> >       /* __khugepaged_exit() must not run from under us */
> > -     VM_BUG_ON_MM(hpage_collapse_test_exit(mm), mm);
> > +     VM_BUG_ON_MM(khugepaged_test_exit(mm), mm);
> >       if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags)))
> >               return;
> >
> > @@ -503,7 +503,7 @@ void __khugepaged_exit(struct mm_struct *mm)
> >       } else if (mm_slot) {
> >               /*
> >                * This is required to serialize against
> > -              * hpage_collapse_test_exit() (which is guaranteed to run
> > +              * khugepaged_test_exit() (which is guaranteed to run
> >                * under mmap sem read mode). Stop here (after we return all
> >                * pagetables will be destroyed) until khugepaged has finished
> >                * working on the pagetables under the mmap_lock.
> > @@ -851,7 +851,7 @@ struct collapse_control khugepaged_collapse_control = {
> >       .is_khugepaged = true,
> >  };
> >
> > -static bool hpage_collapse_scan_abort(int nid, struct collapse_control *cc)
> > +static bool khugepaged_scan_abort(int nid, struct collapse_control *cc)
> >  {
> >       int i;
> >
> > @@ -886,7 +886,7 @@ static inline gfp_t alloc_hugepage_khugepaged_gfpmask(void)
> >  }
> >
> >  #ifdef CONFIG_NUMA
> > -static int hpage_collapse_find_target_node(struct collapse_control *cc)
> > +static int khugepaged_find_target_node(struct collapse_control *cc)
> >  {
> >       int nid, target_node = 0, max_value = 0;
> >
> > @@ -905,7 +905,7 @@ static int hpage_collapse_find_target_node(struct collapse_control *cc)
> >       return target_node;
> >  }
> >  #else
> > -static int hpage_collapse_find_target_node(struct collapse_control *cc)
> > +static int khugepaged_find_target_node(struct collapse_control *cc)
> >  {
> >       return 0;
> >  }
> > @@ -925,7 +925,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
> >       struct vm_area_struct *vma;
> >       unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
> >
> > -     if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
> > +     if (unlikely(khugepaged_test_exit_or_disable(mm)))
> >               return SCAN_ANY_PROCESS;
> >
> >       *vmap = vma = find_vma(mm, address);
> > @@ -992,7 +992,7 @@ static int check_pmd_still_valid(struct mm_struct *mm,
> >
> >  /*
> >   * Bring missing pages in from swap, to complete THP collapse.
> > - * Only done if hpage_collapse_scan_pmd believes it is worthwhile.
> > + * Only done if khugepaged_scan_pmd believes it is worthwhile.
> >   *
> >   * Called and returns without pte mapped or spinlocks held.
> >   * Returns result: if not SCAN_SUCCEED, mmap_lock has been released.
> > @@ -1078,7 +1078,7 @@ static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
> >  {
> >       gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
> >                    GFP_TRANSHUGE);
> > -     int node = hpage_collapse_find_target_node(cc);
> > +     int node = khugepaged_find_target_node(cc);
> >       struct folio *folio;
> >
> >       folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node, &cc->alloc_nmask);
> > @@ -1264,7 +1264,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
> >       return result;
> >  }
> >
> > -static int hpage_collapse_scan_pmd(struct mm_struct *mm,
> > +static int khugepaged_scan_pmd(struct mm_struct *mm,
> >                                  struct vm_area_struct *vma,
> >                                  unsigned long address, bool *mmap_locked,
> >                                  struct collapse_control *cc)
> > @@ -1378,7 +1378,7 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
> >                * hit record.
> >                */
> >               node = folio_nid(folio);
> > -             if (hpage_collapse_scan_abort(node, cc)) {
> > +             if (khugepaged_scan_abort(node, cc)) {
> >                       result = SCAN_SCAN_ABORT;
> >                       goto out_unmap;
> >               }
> > @@ -1447,7 +1447,7 @@ static void collect_mm_slot(struct khugepaged_mm_slot *mm_slot)
> >
> >       lockdep_assert_held(&khugepaged_mm_lock);
> >
> > -     if (hpage_collapse_test_exit(mm)) {
> > +     if (khugepaged_test_exit(mm)) {
> >               /* free mm_slot */
> >               hash_del(&slot->hash);
> >               list_del(&slot->mm_node);
> > @@ -1740,7 +1740,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
> >               if (find_pmd_or_thp_or_none(mm, addr, &pmd) != SCAN_SUCCEED)
> >                       continue;
> >
> > -             if (hpage_collapse_test_exit(mm))
> > +             if (khugepaged_test_exit(mm))
> >                       continue;
> >               /*
> >                * When a vma is registered with uffd-wp, we cannot recycle
> > @@ -2262,7 +2262,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
> >       return result;
> >  }
> >
> > -static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
> > +static int khugepaged_scan_file(struct mm_struct *mm, unsigned long addr,
> >                                   struct file *file, pgoff_t start,
> >                                   struct collapse_control *cc)
> >  {
> > @@ -2307,7 +2307,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
> >               }
> >
> >               node = folio_nid(folio);
> > -             if (hpage_collapse_scan_abort(node, cc)) {
> > +             if (khugepaged_scan_abort(node, cc)) {
> >                       result = SCAN_SCAN_ABORT;
> >                       break;
> >               }
> > @@ -2391,7 +2391,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> >               goto breakouterloop_mmap_lock;
> >
> >       progress++;
> > -     if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
> > +     if (unlikely(khugepaged_test_exit_or_disable(mm)))
> >               goto breakouterloop;
> >
> >       vma_iter_init(&vmi, mm, khugepaged_scan.address);
> > @@ -2399,7 +2399,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> >               unsigned long hstart, hend;
> >
> >               cond_resched();
> > -             if (unlikely(hpage_collapse_test_exit_or_disable(mm))) {
> > +             if (unlikely(khugepaged_test_exit_or_disable(mm))) {
> >                       progress++;
> >                       break;
> >               }
> > @@ -2421,7 +2421,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> >                       bool mmap_locked = true;
> >
> >                       cond_resched();
> > -                     if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
> > +                     if (unlikely(khugepaged_test_exit_or_disable(mm)))
> >                               goto breakouterloop;
> >
> >                       VM_BUG_ON(khugepaged_scan.address < hstart ||
> > @@ -2481,7 +2481,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> >        * Release the current mm_slot if this mm is about to die, or
> >        * if we scanned all vmas of this mm.
> >        */
> > -     if (hpage_collapse_test_exit(mm) || !vma) {
> > +     if (khugepaged_test_exit(mm) || !vma) {
> >               /*
> >                * Make sure that if mm_users is reaching zero while
> >                * khugepaged runs here, khugepaged_exit will find
> > --
> > 2.49.0
> >
>