diff options
| -rw-r--r-- | include/linux/mm.h | 22 | ||||
| -rw-r--r-- | mm/memory.c | 31 |
2 files changed, 40 insertions, 13 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 6eb7f48..82d7024 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -625,10 +625,16 @@ static inline int page_mapped(struct page *page) * Used to decide whether a process gets delivered SIGBUS or * just gets major/minor fault counters bumped up. */ -#define VM_FAULT_OOM (-1) -#define VM_FAULT_SIGBUS 0 -#define VM_FAULT_MINOR 1 -#define VM_FAULT_MAJOR 2 +#define VM_FAULT_OOM 0x00 +#define VM_FAULT_SIGBUS 0x01 +#define VM_FAULT_MINOR 0x02 +#define VM_FAULT_MAJOR 0x03 + +/* + * Special case for get_user_pages. + * Must be in a distinct bit from the above VM_FAULT_ flags. + */ +#define VM_FAULT_WRITE 0x10 #define offset_in_page(p) ((unsigned long)(p) & ~PAGE_MASK) @@ -704,7 +710,13 @@ extern pte_t *FASTCALL(pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsign extern pte_t *FASTCALL(pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long address)); extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot); extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot); -extern int handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access); +extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access); + +static inline int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, int write_access) +{ + return __handle_mm_fault(mm, vma, address, write_access) & (~VM_FAULT_WRITE); +} + extern int make_pages_present(unsigned long addr, unsigned long end); extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); void install_arg_page(struct vm_area_struct *, struct page *, unsigned long); diff --git a/mm/memory.c b/mm/memory.c index 2405289..81d7117 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 +944,11 @@ 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))) { /* * Shortcut for anonymous pages. We don't want * to force the creation of pages tables for @@ -957,7 +961,16 @@ 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)) { + switch (__handle_mm_fault(mm, vma, start, + write_access)) { + case VM_FAULT_WRITE: + /* + * do_wp_page has broken COW when + * necessary, even if maybe_mkwrite + * decided not to set pte_write + */ + write_access = 0; + /* FALLTHRU */ case VM_FAULT_MINOR: tsk->min_flt++; break; @@ -1220,6 +1233,7 @@ 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 +1261,7 @@ 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 +1288,7 @@ 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 +1305,13 @@ 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 +2003,6 @@ 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 +2017,7 @@ 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; |
