| Message ID | 20220615172926.546974-4-shy828301@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Cleanup transhuge_xxx helpers | expand |
On 15 Jun 10:29, Yang Shi wrote: > The hugepage_vma_revalidate() needs to check if the vma is still > anonymous vma or not since the address may be unmapped then remapped to > file before khugepaged reaquired the mmap_lock. > > The old comment is not quite helpful, elaborate this with better > comment. > > Signed-off-by: Yang Shi <shy828301@gmail.com> > --- > mm/khugepaged.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index db0b334a7d1f..5baa394e34c8 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -960,7 +960,13 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > return SCAN_ADDRESS_RANGE; > if (!hugepage_vma_check(vma, vma->vm_flags)) > return SCAN_VMA_CHECK; > - /* Anon VMA expected */ > + /* > + * Anon VMA expected, the address may be unmapped then > + * remapped to file after khugepaged reaquired the mmap_lock. > + * > + * hugepage_vma_check may return true for qualified file > + * vmas. > + */ > if (!vma->anon_vma || !vma_is_anonymous(vma)) > return SCAN_VMA_CHECK; > return 0; > -- > 2.26.3 > Reviewed-by: Zach O'Keefe <zokeefe@google.com>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c index db0b334a7d1f..5baa394e34c8 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -960,7 +960,13 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, return SCAN_ADDRESS_RANGE; if (!hugepage_vma_check(vma, vma->vm_flags)) return SCAN_VMA_CHECK; - /* Anon VMA expected */ + /* + * Anon VMA expected, the address may be unmapped then + * remapped to file after khugepaged reaquired the mmap_lock. + * + * hugepage_vma_check may return true for qualified file + * vmas. + */ if (!vma->anon_vma || !vma_is_anonymous(vma)) return SCAN_VMA_CHECK; return 0;
The hugepage_vma_revalidate() needs to check if the vma is still anonymous vma or not since the address may be unmapped then remapped to file before khugepaged reaquired the mmap_lock. The old comment is not quite helpful, elaborate this with better comment. Signed-off-by: Yang Shi <shy828301@gmail.com> --- mm/khugepaged.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)