diff options
| -rw-r--r-- | mm/memory.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/mm/memory.c b/mm/memory.c index 81d7117aa58..e046b7e4b53 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -949,6 +949,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, cond_resched_lock(&mm->page_table_lock); 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 @@ -961,16 +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_access)) { - case VM_FAULT_WRITE: - /* - * do_wp_page has broken COW when - * necessary, even if maybe_mkwrite - * decided not to set pte_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; - /* FALLTHRU */ + + switch (ret & ~VM_FAULT_WRITE) { case VM_FAULT_MINOR: tsk->min_flt++; break; |