| Message ID | 20250331081327.256412-5-bhe@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/gup: Minor fix, cleanup and improvements | expand |
On 31.03.25 10:13, Baoquan He wrote: > In the current kernel, only pud huge page is supported in some > architectures. P4d and pgd huge pages haven't been supported yet. > And in mm/gup.c, there's no pgd huge page handling in the > follow_page_mask() code path. Hence it doesn't make sense to have > gup_fast_pgd_leaf() in gup_fast code path. I wonder if that was in place to handle (prepare for) very large hugetlb folios. Until a while ago, follow_page_mask() did not have to handle these hugetlb folios. But I assume it never got used. Acked-by: David Hildenbrand <david@redhat.com> > > Here remove gup_fast_pgd_leaf() and clean up the relevant codes. > > Signed-off-by: Baoquan He <bhe@redhat.com> > --- > mm/gup.c | 49 +++---------------------------------------------- > 1 file changed, 3 insertions(+), 46 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index a15317cf6641..58cdc5605a4a 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -3168,46 +3168,6 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, > return 1; > } > > -static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr, > - unsigned long end, unsigned int flags, struct page **pages, > - int *nr) > -{ > - int refs; > - struct page *page; > - struct folio *folio; > - > - if (!pgd_access_permitted(orig, flags & FOLL_WRITE)) > - return 0; > - > - BUILD_BUG_ON(pgd_devmap(orig)); > - > - page = pgd_page(orig); > - refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr); > - > - folio = try_grab_folio_fast(page, refs, flags); > - if (!folio) > - return 0; > - > - if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - if (!gup_fast_folio_allowed(folio, flags)) { > - gup_put_folio(folio, refs, flags); > - return 0; > - } > - > - *nr += refs; > - folio_set_referenced(folio); > - return 1; > -} > - > static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, > unsigned long end, unsigned int flags, struct page **pages, > int *nr) > @@ -3302,12 +3262,9 @@ static void gup_fast_pgd_range(unsigned long addr, unsigned long end, > next = pgd_addr_end(addr, end); > if (pgd_none(pgd)) > return; > - if (unlikely(pgd_leaf(pgd))) { > - if (!gup_fast_pgd_leaf(pgd, pgdp, addr, next, flags, > - pages, nr)) > - return; > - } else if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, > - pages, nr)) > + BUILD_BUG_ON(pgd_leaf(pgd)); > + if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, > + pages, nr)) > return; > } while (pgdp++, addr = next, addr != end); > }
On Mon, Mar 31, 2025 at 04:13:24PM +0800, Baoquan He wrote: > In the current kernel, only pud huge page is supported in some > architectures. P4d and pgd huge pages haven't been supported yet. > And in mm/gup.c, there's no pgd huge page handling in the > follow_page_mask() code path. Hence it doesn't make sense to have > gup_fast_pgd_leaf() in gup_fast code path. > > Here remove gup_fast_pgd_leaf() and clean up the relevant codes. > > Signed-off-by: Baoquan He <bhe@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de>
diff --git a/mm/gup.c b/mm/gup.c index a15317cf6641..58cdc5605a4a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -3168,46 +3168,6 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr, return 1; } -static int gup_fast_pgd_leaf(pgd_t orig, pgd_t *pgdp, unsigned long addr, - unsigned long end, unsigned int flags, struct page **pages, - int *nr) -{ - int refs; - struct page *page; - struct folio *folio; - - if (!pgd_access_permitted(orig, flags & FOLL_WRITE)) - return 0; - - BUILD_BUG_ON(pgd_devmap(orig)); - - page = pgd_page(orig); - refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr); - - folio = try_grab_folio_fast(page, refs, flags); - if (!folio) - return 0; - - if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!pgd_write(orig) && gup_must_unshare(NULL, flags, &folio->page)) { - gup_put_folio(folio, refs, flags); - return 0; - } - - if (!gup_fast_folio_allowed(folio, flags)) { - gup_put_folio(folio, refs, flags); - return 0; - } - - *nr += refs; - folio_set_referenced(folio); - return 1; -} - static int gup_fast_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned long end, unsigned int flags, struct page **pages, int *nr) @@ -3302,12 +3262,9 @@ static void gup_fast_pgd_range(unsigned long addr, unsigned long end, next = pgd_addr_end(addr, end); if (pgd_none(pgd)) return; - if (unlikely(pgd_leaf(pgd))) { - if (!gup_fast_pgd_leaf(pgd, pgdp, addr, next, flags, - pages, nr)) - return; - } else if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, - pages, nr)) + BUILD_BUG_ON(pgd_leaf(pgd)); + if (!gup_fast_p4d_range(pgdp, pgd, addr, next, flags, + pages, nr)) return; } while (pgdp++, addr = next, addr != end); }
In the current kernel, only pud huge page is supported in some architectures. P4d and pgd huge pages haven't been supported yet. And in mm/gup.c, there's no pgd huge page handling in the follow_page_mask() code path. Hence it doesn't make sense to have gup_fast_pgd_leaf() in gup_fast code path. Here remove gup_fast_pgd_leaf() and clean up the relevant codes. Signed-off-by: Baoquan He <bhe@redhat.com> --- mm/gup.c | 49 +++---------------------------------------------- 1 file changed, 3 insertions(+), 46 deletions(-)