[RFC PATCH 02/15] mm/vmalloc: move common logic from __vmalloc_area_node to a separate func

[Roman Penyaev <rpenyaev@xxxxxxx>]

This one moves logic related to pages array creation to a separate
function, which will be used by vrealloc() call as well, which
implementation will follow.

Signed-off-by: Roman Penyaev <rpenyaev@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 mm/vmalloc.c | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4851b4a67f55..ad6cd807f6db 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1662,21 +1662,26 @@ EXPORT_SYMBOL(vmap);
 static void *__vmalloc_node(unsigned long size, unsigned long align,
 			    gfp_t gfp_mask, pgprot_t prot,
 			    int node, const void *caller);
-static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
-				 pgprot_t prot, int node)
+
+static int alloc_vm_area_array(struct vm_struct *area, gfp_t gfp_mask, int node)
 {
+	unsigned int nr_pages, array_size;
 	struct page **pages;
-	unsigned int nr_pages, array_size, i;
+
 	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
-	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
 	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
 					0 :
 					__GFP_HIGHMEM;
 
+	if (WARN_ON(area->pages))
+		return -EINVAL;
+
 	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
+	if (!nr_pages)
+		return -EINVAL;
+
 	array_size = (nr_pages * sizeof(struct page *));
 
-	area->nr_pages = nr_pages;
 	/* Please note that the recursion is strictly bounded. */
 	if (array_size > PAGE_SIZE) {
 		pages = __vmalloc_node(array_size, 1, nested_gfp|highmem_mask,
@@ -1684,8 +1689,25 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	} else {
 		pages = kmalloc_node(array_size, nested_gfp, node);
 	}
+	if (!pages)
+		return -ENOMEM;
+
+	area->nr_pages = nr_pages;
 	area->pages = pages;
-	if (!area->pages) {
+
+	return 0;
+}
+
+static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
+				 pgprot_t prot, int node)
+{
+	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
+	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
+					0 :
+					__GFP_HIGHMEM;
+	unsigned int i;
+
+	if (alloc_vm_area_array(area, gfp_mask, node)) {
 		remove_vm_area(area->addr);
 		kfree(area);
 		return NULL;
@@ -1709,7 +1731,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 			cond_resched();
 	}
 
-	if (map_vm_area(area, prot, pages))
+	if (map_vm_area(area, prot, area->pages))
 		goto fail;
 	return area->addr;
 
-- 
2.19.1