Thanks for this, I've read through page_vma_mapped_walk() a few too many times
recently and it annoyed me enough to start writing some patches to clean it up,
but happy to see this instead.
I confirmed pvmw->page isn't modified here or in map/check_pte(pvmw), so the
patch looks good to me:
Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>
On Thursday, 10 June 2021 4:34:40 PM AEST Hugh Dickins wrote:
> page_vma_mapped_walk() cleanup: sometimes the local copy of pvwm->page was
> used, sometimes pvmw->page itself: use the local copy "page" throughout.
>
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> mm/page_vma_mapped.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index e37bd43904af..a6dbf714ca15 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -156,7 +156,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> if (pvmw->pte)
> goto next_pte;
>
> - if (unlikely(PageHuge(pvmw->page))) {
> + if (unlikely(PageHuge(page))) {
> /* when pud is not present, pte will be NULL */
> pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
> if (!pvmw->pte)
> @@ -217,8 +217,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> * cannot return prematurely, while zap_huge_pmd() has
> * cleared *pmd but not decremented compound_mapcount().
> */
> - if ((pvmw->flags & PVMW_SYNC) &&
> - PageTransCompound(pvmw->page)) {
> + if ((pvmw->flags & PVMW_SYNC) && PageTransCompound(page)) {
> spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);
>
> spin_unlock(ptl);
> @@ -234,9 +233,9 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> return true;
> next_pte:
> /* Seek to next pte only makes sense for THP */
> - if (!PageTransHuge(pvmw->page) || PageHuge(pvmw->page))
> + if (!PageTransHuge(page) || PageHuge(page))
> return not_found(pvmw);
> - end = vma_address_end(pvmw->page, pvmw->vma);
> + end = vma_address_end(page, pvmw->vma);
> do {
> pvmw->address += PAGE_SIZE;
> if (pvmw->address >= end)
> --
> 2.26.2
>
