mlock: do not hold mmap_sem for extended periods of time

[deliverable/linux.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 15e1f19a3b1003a5aa5e0b618766cfe648b3b81d..1bbe9a22429cd442a5981a0c895a5cddd8c7fdfa 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1363,7 +1363,8 @@ no_page_table:
 
 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                     unsigned long start, int nr_pages, unsigned int gup_flags,
-                    struct page **pages, struct vm_area_struct **vmas)
+                    struct page **pages, struct vm_area_struct **vmas,
+                    int *nonblocking)
 {
        int i;
        unsigned long vm_flags;
@@ -1463,10 +1464,15 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                        cond_resched();
                        while (!(page = follow_page(vma, start, foll_flags))) {
                                int ret;
+                               unsigned int fault_flags = 0;
+
+                               if (foll_flags & FOLL_WRITE)
+                                       fault_flags |= FAULT_FLAG_WRITE;
+                               if (nonblocking)
+                                       fault_flags |= FAULT_FLAG_ALLOW_RETRY;
 
                                ret = handle_mm_fault(mm, vma, start,
-                                       (foll_flags & FOLL_WRITE) ?
-                                       FAULT_FLAG_WRITE : 0);
+                                                       fault_flags);
 
                                if (ret & VM_FAULT_ERROR) {
                                        if (ret & VM_FAULT_OOM)
@@ -1482,6 +1488,11 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
                                else
                                        tsk->min_flt++;
 
+                               if (ret & VM_FAULT_RETRY) {
+                                       *nonblocking = 0;
+                                       return i;
+                               }
+
                                /*
                                 * The VM_FAULT_WRITE bit tells us that
                                 * do_wp_page has broken COW when necessary,
@@ -1581,7 +1592,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
        if (force)
                flags |= FOLL_FORCE;
 
-       return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
+       return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
+                               NULL);
 }
 EXPORT_SYMBOL(get_user_pages);
 
@@ -1606,7 +1618,8 @@ struct page *get_dump_page(unsigned long addr)
        struct page *page;
 
        if (__get_user_pages(current, current->mm, addr, 1,
-                       FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
+                            FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
+                            NULL) < 1)
                return NULL;
        flush_cache_page(vma, addr, page_to_pfn(page));
        return page;