Re: [PATCH RESEND v5 1/4] mm/rmap: remove duplicated exit code in pagewalk loop

[Lance Yang]

Hi Baolin,

Thanks for taking time to review!

Best,
Lance

On Tue, May 14, 2024 at 2:26 PM Baolin Wang
<baolin.wang@xxxxxxxxxxxxxxxxx> wrote:
>
>
>
> On 2024/5/13 15:47, Lance Yang wrote:
> > Introduce the labels walk_done and walk_done_err as exit points to
> > eliminate duplicated exit code in the pagewalk loop.
> >
> > Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> > Signed-off-by: Lance Yang <ioworker0@xxxxxxxxx>
>
> LGTM.
> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>
> > ---
> >   mm/rmap.c | 40 +++++++++++++++-------------------------
> >   1 file changed, 15 insertions(+), 25 deletions(-)
> >
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index e8fc5ecb59b2..ddffa30c79fb 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -1679,9 +1679,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                       /* Restore the mlock which got missed */
> >                       if (!folio_test_large(folio))
> >                               mlock_vma_folio(folio, vma);
> > -                     page_vma_mapped_walk_done(&pvmw);
> > -                     ret = false;
> > -                     break;
> > +                     goto walk_done_err;
> >               }
> >
> >               pfn = pte_pfn(ptep_get(pvmw.pte));
> > @@ -1719,11 +1717,8 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                        */
> >                       if (!anon) {
> >                               VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
> > -                             if (!hugetlb_vma_trylock_write(vma)) {
> > -                                     page_vma_mapped_walk_done(&pvmw);
> > -                                     ret = false;
> > -                                     break;
> > -                             }
> > +                             if (!hugetlb_vma_trylock_write(vma))
> > +                                     goto walk_done_err;
> >                               if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) {
> >                                       hugetlb_vma_unlock_write(vma);
> >                                       flush_tlb_range(vma,
> > @@ -1738,8 +1733,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                                        * actual page and drop map count
> >                                        * to zero.
> >                                        */
> > -                                     page_vma_mapped_walk_done(&pvmw);
> > -                                     break;
> > +                                     goto walk_done;
> >                               }
> >                               hugetlb_vma_unlock_write(vma);
> >                       }
> > @@ -1811,9 +1805,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                       if (unlikely(folio_test_swapbacked(folio) !=
> >                                       folio_test_swapcache(folio))) {
> >                               WARN_ON_ONCE(1);
> > -                             ret = false;
> > -                             page_vma_mapped_walk_done(&pvmw);
> > -                             break;
> > +                             goto walk_done_err;
> >                       }
> >
> >                       /* MADV_FREE page check */
> > @@ -1852,23 +1844,17 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                                */
> >                               set_pte_at(mm, address, pvmw.pte, pteval);
> >                               folio_set_swapbacked(folio);
> > -                             ret = false;
> > -                             page_vma_mapped_walk_done(&pvmw);
> > -                             break;
> > +                             goto walk_done_err;
> >                       }
> >
> >                       if (swap_duplicate(entry) < 0) {
> >                               set_pte_at(mm, address, pvmw.pte, pteval);
> > -                             ret = false;
> > -                             page_vma_mapped_walk_done(&pvmw);
> > -                             break;
> > +                             goto walk_done_err;
> >                       }
> >                       if (arch_unmap_one(mm, vma, address, pteval) < 0) {
> >                               swap_free(entry);
> >                               set_pte_at(mm, address, pvmw.pte, pteval);
> > -                             ret = false;
> > -                             page_vma_mapped_walk_done(&pvmw);
> > -                             break;
> > +                             goto walk_done_err;
> >                       }
> >
> >                       /* See folio_try_share_anon_rmap(): clear PTE first. */
> > @@ -1876,9 +1862,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >                           folio_try_share_anon_rmap_pte(folio, subpage)) {
> >                               swap_free(entry);
> >                               set_pte_at(mm, address, pvmw.pte, pteval);
> > -                             ret = false;
> > -                             page_vma_mapped_walk_done(&pvmw);
> > -                             break;
> > +                             goto walk_done_err;
> >                       }
> >                       if (list_empty(&mm->mmlist)) {
> >                               spin_lock(&mmlist_lock);
> > @@ -1918,6 +1902,12 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
> >               if (vma->vm_flags & VM_LOCKED)
> >                       mlock_drain_local();
> >               folio_put(folio);
> > +             continue;
> > +walk_done_err:
> > +             ret = false;
> > +walk_done:
> > +             page_vma_mapped_walk_done(&pvmw);
> > +             break;
> >       }
> >
> >       mmu_notifier_invalidate_range_end(&range);