[PATCH RFC 07/12] mm/gup: Refactor record_subpages() to find 1st small page

Peter Xu
2023-11-16T01:29:45Z

All the fast-gup functions take a tail page to operate, always need to do
page mask calculations before feeding that into record_subpages().

Merge that logic into record_subpages(), so that we always take a head
page, and leave the rest calculation to record_subpages().

Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/gup.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 424d45e1afb3..69dae51f3eb1 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2763,11 +2763,14 @@ static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
}
#endif

-static int record_subpages(struct page *page, unsigned long addr,
- unsigned long end, struct page **pages)
+static int record_subpages(struct page *head, unsigned long sz,
+ unsigned long addr, unsigned long end,
+ struct page **pages)
{
+ struct page *page;
int nr;

+ page = nth_page(head, (addr & (sz - 1)) >> PAGE_SHIFT);
for (nr = 0; addr != end; nr++, addr += PAGE_SIZE)
pages[nr] = nth_page(page, nr);

@@ -2804,8 +2807,8 @@ static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
/* hugepages are never "special" */
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));

- page = nth_page(pte_page(pte), (addr & (sz - 1)) >> PAGE_SHIFT);
- refs = record_subpages(page, addr, end, pages + *nr);
+ page = pte_page(pte);
+ refs = record_subpages(page, sz, addr, end, pages + *nr);

folio = try_grab_folio(page, refs, flags);
if (!folio)
@@ -2870,8 +2873,8 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
pages, nr);
}

- page = nth_page(pmd_page(orig), (addr & ~PMD_MASK) >> PAGE_SHIFT);
- refs = record_subpages(page, addr, end, pages + *nr);
+ page = pmd_page(orig);
+ refs = record_subpages(page, PMD_SIZE, addr, end, pages + *nr);

folio = try_grab_folio(page, refs, flags);
if (!folio)
@@ -2914,8 +2917,8 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
pages, nr);
}

- page = nth_page(pud_page(orig), (addr & ~PUD_MASK) >> PAGE_SHIFT);
- refs = record_subpages(page, addr, end, pages + *nr);
+ page = pud_page(orig);
+ refs = record_subpages(page, PUD_SIZE, addr, end, pages + *nr);

folio = try_grab_folio(page, refs, flags);
if (!folio)
@@ -2954,8 +2957,8 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,

BUILD_BUG_ON(pgd_devmap(orig));

- page = nth_page(pgd_page(orig), (addr & ~PGDIR_MASK) >> PAGE_SHIFT);
- refs = record_subpages(page, addr, end, pages + *nr);
+ page = pgd_page(orig);
+ refs = record_subpages(page, PGDIR_SIZE, addr, end, pages + *nr);

folio = try_grab_folio(page, refs, flags);
if (!folio)
--
2.41.0