From d6d6d21dbf435d8030782a627175e36e6c7b2dfb Mon Sep 17 00:00:00 2001
From: David Hildenbrand <redacted>
Date: Sat, 6 Sep 2025 08:33:42 +0200
Subject: [PATCH] tmp

Signed-off-by: David Hildenbrand <redacted>
---
  mm/gup.c | 79 ++++++++++++++++++++++++++------------------------------
  1 file changed, 36 insertions(+), 43 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 22420f2069ee1..98907ead749c0 100644
--- a/mm/gup.c
+++ b/mm/gup.c

@@ -2845,12 +2845,11 @@ static void __maybe_unused 

gup_fast_undo_dev_pagemap(int *nr, int nr_start,
   * also check pmd here to make sure pmd doesn't change (corresponds to
   * pmdp_collapse_flush() in the THP collapse code path).
   */
-static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
-        unsigned long end, unsigned int flags, struct page **pages,
-        int *nr)
+static unsigned long gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, 
unsigned long addr,
+        unsigned long end, unsigned int flags, struct page **pages)
  {
      struct dev_pagemap *pgmap = NULL;
-    int ret = 0;
+    unsigned long nr_pages = 0;
      pte_t *ptep, *ptem;

      ptem = ptep = pte_offset_map(&pmd, addr);

@@ -2908,24 +2907,20 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t 

*pmdp, unsigned long addr,
           * details.
           */
          if (flags & FOLL_PIN) {
-            ret = arch_make_folio_accessible(folio);
-            if (ret) {
+            if (arch_make_folio_accessible(folio)) {
                  gup_put_folio(folio, 1, flags);
                  goto pte_unmap;
              }
          }
          folio_set_referenced(folio);
-        pages[*nr] = page;
-        (*nr)++;
+        pages[nr_pages++] = page;
      } while (ptep++, addr += PAGE_SIZE, addr != end);

-    ret = 1;
-
  pte_unmap:
      if (pgmap)
          put_dev_pagemap(pgmap);
      pte_unmap(ptem);
-    return ret;
+    return nr_pages;
  }
  #else

@@ -2938,21 +2933,24 @@ static int gup_fast_pte_range(pmd_t pmd, pmd_t 

*pmdp, unsigned long addr,
   * get_user_pages_fast_only implementation that can pin pages. Thus 
it's still
   * useful to have gup_fast_pmd_leaf even if we can't operate on ptes.
   */
-static int gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
-        unsigned long end, unsigned int flags, struct page **pages,
-        int *nr)
+static unsigned long gup_fast_pte_range(pmd_t pmd, pmd_t *pmdp, 
unsigned long addr,
+        unsigned long end, unsigned int flags, struct page **pages)
  {
      return 0;
  }
  #endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */

-static int gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, unsigned long addr,
-        unsigned long end, unsigned int flags, struct page **pages,
-        int *nr)
+static unsigned long gup_fast_pmd_leaf(pmd_t orig, pmd_t *pmdp, 
unsigned long addr,
+        unsigned long end, unsigned int flags, struct page **pages)
  {
+    const unsigned long nr_pages = (end - addr) >> PAGE_SHIFT;
      struct page *page;
      struct folio *folio;
-    int refs;
+    unsigned long i;
+
+    /* See gup_fast_pte_range() */
+    if (pmd_protnone(orig))
+        return 0;

      if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
          return 0;

@@ -2960,33 +2958,30 @@ static int gup_fast_pmd_leaf(pmd_t orig, pmd_t 

*pmdp, unsigned long addr,
      if (pmd_special(orig))
          return 0;

-    refs = (end - addr) >> PAGE_SHIFT;
      page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);

-    folio = try_grab_folio_fast(page, refs, flags);
+    folio = try_grab_folio_fast(page, nr_pages, flags);
      if (!folio)
          return 0;

      if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
-        gup_put_folio(folio, refs, flags);
+        gup_put_folio(folio, nr_pages, flags);
          return 0;
      }

      if (!gup_fast_folio_allowed(folio, flags)) {
-        gup_put_folio(folio, refs, flags);
+        gup_put_folio(folio, nr_pages, flags);
          return 0;
      }
      if (!pmd_write(orig) && gup_must_unshare(NULL, flags, &folio- 
 >page)) {
-        gup_put_folio(folio, refs, flags);
+        gup_put_folio(folio, nr_pages, flags);
          return 0;
      }

-    pages += *nr;
-    *nr += refs;
-    for (; refs; refs--)
+    for (i = 0; i < nr_pages; i++)
          *(pages++) = page++;
      folio_set_referenced(folio);
-    return 1;
+    return nr_pages;
  }

  static int gup_fast_pud_leaf(pud_t orig, pud_t *pudp, unsigned long addr,

@@ -3033,11 +3028,11 @@ static int gup_fast_pud_leaf(pud_t orig, pud_t 

*pudp, unsigned long addr,
      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)
+static unsigned long gup_fast_pmd_range(pud_t *pudp, pud_t pud, 
unsigned long addr,
+        unsigned long end, unsigned int flags, struct page **pages)
  {
-    unsigned long next;
+    unsigned long cur_nr_pages, next;
+    unsigned long nr_pages = 0;
      pmd_t *pmdp;

      pmdp = pmd_offset_lockless(pudp, pud, addr);

@@ -3046,23 +3041,21 @@ static int gup_fast_pmd_range(pud_t *pudp, pud_t 

pud, unsigned long addr,

          next = pmd_addr_end(addr, end);
          if (!pmd_present(pmd))
-            return 0;
+            break;

-        if (unlikely(pmd_leaf(pmd))) {
-            /* See gup_fast_pte_range() */
-            if (pmd_protnone(pmd))
-                return 0;
+        if (unlikely(pmd_leaf(pmd)))
+            cur_nr_pages = gup_fast_pmd_leaf(pmd, pmdp, addr, next, 
flags, pages);
+        else
+            cur_nr_pages = gup_fast_pte_range(pmd, pmdp, addr, next, 
flags, pages);

-            if (!gup_fast_pmd_leaf(pmd, pmdp, addr, next, flags,
-                pages, nr))
-                return 0;
+        nr_pages += cur_nr_pages;
+        pages += cur_nr_pages;

-        } else if (!gup_fast_pte_range(pmd, pmdp, addr, next, flags,
-                           pages, nr))
-            return 0;
+        if (nr_pages != (next - addr) >> PAGE_SIZE)
+            break;
      } while (pmdp++, addr = next, addr != end);

-    return 1;
+    return nr_pages;
  }

  static int gup_fast_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr,