Merge tag 'thermal-v5.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal...

[linux-2.6-microblaze.git] / mm / gup.c

diff --git a/mm/gup.c b/mm/gup.c
index 39e58df..e5739a1 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -381,22 +381,13 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
 }
 
 /*
- * FOLL_FORCE or a forced COW break can write even to unwritable pte's,
- * but only after we've gone through a COW cycle and they are dirty.
+ * FOLL_FORCE can write to even unwritable pte's, but only
+ * after we've gone through a COW cycle and they are dirty.
  */
 static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
 {
-       return pte_write(pte) || ((flags & FOLL_COW) && pte_dirty(pte));
-}
-
-/*
- * A (separate) COW fault might break the page the other way and
- * get_user_pages() would return the page from what is now the wrong
- * VM. So we need to force a COW break at GUP time even for reads.
- */
-static inline bool should_force_cow_break(struct vm_area_struct *vma, unsigned int flags)
-{
-       return is_cow_mapping(vma->vm_flags) && (flags & (FOLL_GET | FOLL_PIN));
+       return pte_write(pte) ||
+               ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
 }
 
 static struct page *follow_page_pte(struct vm_area_struct *vma,
@@ -843,7 +834,7 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
                        goto unmap;
                *page = pte_page(*pte);
        }
-       if (unlikely(!try_get_page(*page))) {
+       if (unlikely(!try_grab_page(*page, gup_flags))) {
                ret = -ENOMEM;
                goto unmap;
        }
@@ -1067,11 +1058,9 @@ static long __get_user_pages(struct mm_struct *mm,
                                goto out;
                        }
                        if (is_vm_hugetlb_page(vma)) {
-                               if (should_force_cow_break(vma, foll_flags))
-                                       foll_flags |= FOLL_WRITE;
                                i = follow_hugetlb_page(mm, vma, pages, vmas,
                                                &start, &nr_pages, i,
-                                               foll_flags, locked);
+                                               gup_flags, locked);
                                if (locked && *locked == 0) {
                                        /*
                                         * We've got a VM_FAULT_RETRY
@@ -1085,10 +1074,6 @@ static long __get_user_pages(struct mm_struct *mm,
                                continue;
                        }
                }
-
-               if (should_force_cow_break(vma, foll_flags))
-                       foll_flags |= FOLL_WRITE;
-
 retry:
                /*
                 * If we have a pending SIGKILL, don't keep faulting pages and
@@ -1637,7 +1622,7 @@ check_again:
                                        mod_node_page_state(page_pgdat(head),
                                                            NR_ISOLATED_ANON +
                                                            page_is_file_lru(head),
-                                                           hpage_nr_pages(head));
+                                                           thp_nr_pages(head));
                                }
                        }
                }
@@ -2689,19 +2674,6 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
                return -EFAULT;
 
        /*
-        * The FAST_GUP case requires FOLL_WRITE even for pure reads,
-        * because get_user_pages() may need to cause an early COW in
-        * order to avoid confusing the normal COW routines. So only
-        * targets that are already writable are safe to do by just
-        * looking at the page tables.
-        *
-        * NOTE! With FOLL_FAST_ONLY we allow read-only gup_fast() here,
-        * because there is no slow path to fall back on. But you'd
-        * better be careful about possible COW pages - you'll get _a_
-        * COW page, but not necessarily the one you intended to get
-        * depending on what COW event happens after this. COW may break
-        * the page copy in a random direction.
-        *
         * Disable interrupts. The nested form is used, in order to allow
         * full, general purpose use of this routine.
         *
@@ -2714,8 +2686,6 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
         */
        if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) {
                unsigned long fast_flags = gup_flags;
-               if (!(gup_flags & FOLL_FAST_ONLY))
-                       fast_flags |= FOLL_WRITE;
 
                local_irq_save(flags);
                gup_pgd_range(addr, end, fast_flags, pages, &nr_pinned);