Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf

[karo-tx-linux.git] / mm / util.c

diff --git a/mm/util.c b/mm/util.c
index 9af1c12b310c7f092f030fc1a4303c287724b0a6..6d1f9200f74e794c403ec687bae513e4f6e40700 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -176,6 +176,37 @@ char *strndup_user(const char __user *s, long n)
 }
 EXPORT_SYMBOL(strndup_user);
 
+/**
+ * memdup_user_nul - duplicate memory region from user space and NUL-terminate
+ *
+ * @src: source address in user space
+ * @len: number of bytes to copy
+ *
+ * Returns an ERR_PTR() on failure.
+ */
+void *memdup_user_nul(const void __user *src, size_t len)
+{
+       char *p;
+
+       /*
+        * Always use GFP_KERNEL, since copy_from_user() can sleep and
+        * cause pagefault, which makes it pointless to use GFP_NOFS
+        * or GFP_ATOMIC.
+        */
+       p = kmalloc_track_caller(len + 1, GFP_KERNEL);
+       if (!p)
+               return ERR_PTR(-ENOMEM);
+
+       if (copy_from_user(p, src, len)) {
+               kfree(p);
+               return ERR_PTR(-EFAULT);
+       }
+       p[len] = '\0';
+
+       return p;
+}
+EXPORT_SYMBOL(memdup_user_nul);
+
 void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
                struct vm_area_struct *prev, struct rb_node *rb_parent)
 {
@@ -355,7 +386,9 @@ struct anon_vma *page_anon_vma(struct page *page)
 
 struct address_space *page_mapping(struct page *page)
 {
-       unsigned long mapping;
+       struct address_space *mapping;
+
+       page = compound_head(page);
 
        /* This happens if someone calls flush_dcache_page on slab page */
        if (unlikely(PageSlab(page)))
@@ -368,11 +401,25 @@ struct address_space *page_mapping(struct page *page)
                return swap_address_space(entry);
        }
 
-       mapping = (unsigned long)page->mapping;
-       if (mapping & PAGE_MAPPING_FLAGS)
+       mapping = page->mapping;
+       if ((unsigned long)mapping & PAGE_MAPPING_FLAGS)
                return NULL;
-       return page->mapping;
+       return mapping;
+}
+
+/* Slow path of page_mapcount() for compound pages */
+int __page_mapcount(struct page *page)
+{
+       int ret;
+
+       ret = atomic_read(&page->_mapcount) + 1;
+       page = compound_head(page);
+       ret += atomic_read(compound_mapcount_ptr(page)) + 1;
+       if (PageDoubleMap(page))
+               ret--;
+       return ret;
 }
+EXPORT_SYMBOL_GPL(__page_mapcount);
 
 int overcommit_ratio_handler(struct ctl_table *table, int write,
                             void __user *buffer, size_t *lenp,