diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c index 6d0cc90401c0..968d9b2705d0 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c @@ -619,14 +619,6 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN); - /* - * Using __get_user_pages_fast() with a read-only - * access is questionable. A read-only page may be - * COW-broken, and then this might end up giving - * the wrong side of the COW.. - * - * We may or may not care. - */ if (pvec) /* defer to worker if malloc fails */ pinned = __get_user_pages_fast(obj->userptr.ptr, num_pages, diff --git a/mm/gup.c b/mm/gup.c index 4a8e969a6e59..0f7a806904ae 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -161,12 +161,13 @@ 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)); + return pte_write(pte) || + ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte)); } /* @@ -832,18 +833,12 @@ static long __get_user_pages(struct task_struct *tsk, 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, nonblocking); + gup_flags, nonblocking); 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 @@ -2440,17 +2435,10 @@ int get_user_pages_fast(unsigned long start, int nr_pages, if (unlikely(!access_ok((void __user *)start, len))) 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. - */ if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { local_irq_disable(); - gup_pgd_range(addr, end, gup_flags | FOLL_WRITE, pages, &nr); + gup_pgd_range(addr, end, gup_flags, pages, &nr); local_irq_enable(); ret = nr; } diff --git a/mm/huge_memory.c b/mm/huge_memory.c index e7b6c3d0447a..d29fc49aca1d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1454,12 +1454,13 @@ out_unlock: } /* - * FOLL_FORCE or a forced COW break can write even to unwritable pmd's, - * but only after we've gone through a COW cycle and they are dirty. + * FOLL_FORCE can write to even unwritable pmd's, but only + * after we've gone through a COW cycle and they are dirty. */ static inline bool can_follow_write_pmd(pmd_t pmd, unsigned int flags) { - return pmd_write(pmd) || ((flags & FOLL_COW) && pmd_dirty(pmd)); + return pmd_write(pmd) || + ((flags & FOLL_FORCE) && (flags & FOLL_COW) && pmd_dirty(pmd)); } struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, diff --git a/mm/memory.c b/mm/memory.c index 5b974bbe9c24..2396e1608770 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2771,8 +2771,8 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) * page count reference, and the page is locked, * it's dark out, and we're wearing sunglasses. Hit it. */ - wp_page_reuse(vmf); unlock_page(page); + wp_page_reuse(vmf); return VM_FAULT_WRITE; } else if (unlikely((vmf->vma_flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED))) {