On Tue, 21 Jun 2022 11:58:34 -0700 "Zach O'Keefe" <zokeefe@xxxxxxxxxx> wrote:
> > -bool transparent_hugepage_active(struct vm_area_struct *vma)
> > +bool hugepage_vma_check(struct vm_area_struct *vma,
> > + unsigned long vm_flags,
> > + bool smaps)
> > {
> > - /* The addr is used to check if the vma size fits */
> > - unsigned long addr = (vma->vm_end & HPAGE_PMD_MASK) - HPAGE_PMD_SIZE;
> > + if (!transhuge_vma_enabled(vma, vm_flags))
> > + return false;
> > +
>
> During testing my work on top this patch, I found a small bug here.
>
> Namely, transhuge_vma_enabled() will check vma->vm_mm->flags (to see if
> MMF_DISABLE_THP is set); however, for vDSO vmas, vma->vm_mm is NULL.
>
> Previously, transparent_hugepage_active() in smaps path would check
> transhuge_vma_suitable() before checking these flags, which would fail for vDSO
> vma since we'd take the !vma_is_anonymous() branch and find the vma (most
> likely) wasn't suitably aligned (by chance ?).
>
> Anyways, I think we need to check vma->vm_mm.
Like this?
--- a/mm/huge_memory.c~mm-thp-kill-transparent_hugepage_active-fix
+++ a/mm/huge_memory.c
@@ -73,6 +73,9 @@ bool hugepage_vma_check(struct vm_area_s
unsigned long vm_flags,
bool smaps)
{
+ if (!vma->vm_mm)
+ return false;
+
if (!transhuge_vma_enabled(vma, vm_flags))
return false;
_
