diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/mm/memory.c b/mm/memory.c index 5331e67..29c8112 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1436,6 +1436,16 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, } EXPORT_SYMBOL_GPL(zap_vma_ptes); +/* + * 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_FORCE) && (flags & FOLL_COW) && pte_dirty(pte)); +} + /** * follow_page - look up a page descriptor from a user-virtual address * @vma: vm_area_struct mapping @address @@ -1518,7 +1528,7 @@ split_fallthrough: pte = *ptep; if (!pte_present(pte)) goto no_page; - if ((flags & FOLL_WRITE) && !pte_write(pte)) + if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) goto unlock; page = vm_normal_page(vma, address, pte); @@ -1832,7 +1842,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, */ if ((ret & VM_FAULT_WRITE) && !(vma->vm_flags & VM_WRITE)) - foll_flags &= ~FOLL_WRITE; + foll_flags |= FOLL_COW; cond_resched(); } @@ -3140,7 +3150,8 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, mem_cgroup_commit_charge_swapin(page, ptr); swap_free(entry); - if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) + if ((PageSwapCache(page) && vm_swap_full(page_swap_info(page))) || + (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) try_to_free_swap(page); unlock_page(page); if (swapcache) { |