[PATCH 1/9] mm: Introduce new vm_insert_range API

On 11/15/18 7:45 AM, Souptick Joarder wrote:

Previouly drivers have their own way of mapping range of
kernel pages/memory into user vma and this was done by
invoking vm_insert_page() within a loop.

As this pattern is common across different drivers, it can
be generalized by creating a new function and use it across
the drivers.

vm_insert_range is the new API which will be used to map a
range of kernel memory/pages to user vma.

Signed-off-by: Souptick Joarder <redacted>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/mm_types.h |  3 +++
 mm/memory.c              | 28 ++++++++++++++++++++++++++++
 mm/nommu.c               |  7 +++++++
 3 files changed, 38 insertions(+)

Hi,

What is the opposite of vm_insert_range() or even of vm_insert_page()?
or is there no need for that?

s/no./number/

+ *
+ * This allows drivers to insert range of kernel pages they've allocated
+ * into a user vma. This is a generic function which drivers can use
+ * rather than using their own way of mapping range of kernel pages into
+ * user vma.
+ */
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+			struct page **pages, unsigned long page_count)
+{
+	unsigned long uaddr = addr;
+	int ret = 0, i;
+
+	for (i = 0; i < page_count; i++) {
+		ret = vm_insert_page(vma, uaddr, pages[i]);
+		if (ret < 0)
+			return ret;

For a non-trivial value of page_count:
Is it a problem if vm_insert_page() succeeds for several pages
and then fails?

+		uaddr += PAGE_SIZE;
+	}
+
+	return ret;
+}
+
+/**
  * vm_insert_page - insert single page into user vma
  * @vma: user vma to map to
  * @addr: target user address of this page

thanks.
-- 
~Randy