Re: [PATCH] mm: khugepaged: skip huge page collapse for special files

[Andrew Morton]

On Wed, 27 Oct 2021 13:44:37 -0700 Yang Shi <shy828301@xxxxxxxxx> wrote:

> > > --- a/mm/khugepaged.c
> > > +++ b/mm/khugepaged.c
> > > @@ -445,22 +445,25 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
> > >       if (!transhuge_vma_enabled(vma, vm_flags))
> > >               return false;
> > >
> > > -     /* Enabled via shmem mount options or sysfs settings. */
> > > -     if (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) {
> > > +     if (vma->vm_file)
> > >               return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
> > >                               HPAGE_PMD_NR);
> >
> > Am I misreading this? If we return here for vma->vm_file, the following
> > logic (shmem_file(), etc.) would be skipped, no?
> 
> Oh, yes, you are right. My mistake.
> 
> Andrew,
> 
> Could you please apply the below fix?

um, how well tested are these changes?