diff options
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 35 |
1 files changed, 27 insertions, 8 deletions
diff --git a/mm/memory.c b/mm/memory.c index 2405289dfdf8..e046b7e4b530 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -811,15 +811,18 @@ static struct page *__follow_page(struct mm_struct *mm, unsigned long address, pte = *ptep; pte_unmap(ptep); if (pte_present(pte)) { - if (write && !pte_dirty(pte)) + if (write && !pte_write(pte)) goto out; if (read && !pte_read(pte)) goto out; pfn = pte_pfn(pte); if (pfn_valid(pfn)) { page = pfn_to_page(pfn); - if (accessed) + if (accessed) { + if (write && !pte_dirty(pte) &&!PageDirty(page)) + set_page_dirty(page); mark_page_accessed(page); + } return page; } } @@ -941,10 +944,13 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, } spin_lock(&mm->page_table_lock); do { + int write_access = write; struct page *page; cond_resched_lock(&mm->page_table_lock); - while (!(page = follow_page(mm, start, write))) { + while (!(page = follow_page(mm, start, write_access))) { + int ret; + /* * Shortcut for anonymous pages. We don't want * to force the creation of pages tables for @@ -957,7 +963,18 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, break; } spin_unlock(&mm->page_table_lock); - switch (handle_mm_fault(mm,vma,start,write)) { + ret = __handle_mm_fault(mm, vma, start, write_access); + + /* + * The VM_FAULT_WRITE bit tells us that do_wp_page has + * broken COW when necessary, even if maybe_mkwrite + * decided not to set pte_write. We can thus safely do + * subsequent page lookups as if they were reads. + */ + if (ret & VM_FAULT_WRITE) + write_access = 0; + + switch (ret & ~VM_FAULT_WRITE) { case VM_FAULT_MINOR: tsk->min_flt++; break; @@ -1220,6 +1237,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, struct page *old_page, *new_page; unsigned long pfn = pte_pfn(pte); pte_t entry; + int ret; if (unlikely(!pfn_valid(pfn))) { /* @@ -1247,7 +1265,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, lazy_mmu_prot_update(entry); pte_unmap(page_table); spin_unlock(&mm->page_table_lock); - return VM_FAULT_MINOR; + return VM_FAULT_MINOR|VM_FAULT_WRITE; } } pte_unmap(page_table); @@ -1274,6 +1292,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, /* * Re-check the pte - we dropped the lock */ + ret = VM_FAULT_MINOR; spin_lock(&mm->page_table_lock); page_table = pte_offset_map(pmd, address); if (likely(pte_same(*page_table, pte))) { @@ -1290,12 +1309,13 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma, /* Free the old page.. */ new_page = old_page; + ret |= VM_FAULT_WRITE; } pte_unmap(page_table); page_cache_release(new_page); page_cache_release(old_page); spin_unlock(&mm->page_table_lock); - return VM_FAULT_MINOR; + return ret; no_new_page: page_cache_release(old_page); @@ -1987,7 +2007,6 @@ static inline int handle_pte_fault(struct mm_struct *mm, if (write_access) { if (!pte_write(entry)) return do_wp_page(mm, vma, address, pte, pmd, entry); - entry = pte_mkdirty(entry); } entry = pte_mkyoung(entry); @@ -2002,7 +2021,7 @@ static inline int handle_pte_fault(struct mm_struct *mm, /* * By the time we get here, we already hold the mm semaphore */ -int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, +int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, unsigned long address, int write_access) { pgd_t *pgd; |
