[PATCH 1/2] mm: cma: fix the name of CMA areas

[Barry Song]

if users give a name saved in stack, the current code will generate magic
pointer.
if users don't give a name(NULL), kasprintf() will always return NULL as
we are at the early stage. that means cma_init_reserved_mem() will return
-ENOMEM if users set name parameter as NULL.

Cc: Roman Gushchin <g...@fb.com>
Signed-off-by: Barry Song <song.bao....@hisilicon.com>
---
 mm/cma.c | 13 ++++++-------
 mm/cma.h |  4 +++-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index 0463ad2ce06b..b24151fa2101 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -202,13 +202,12 @@ int __init cma_init_reserved_mem(phys_addr_t base, 
phys_addr_t size,
         * subsystems (like slab allocator) are available.
         */
        cma = &cma_areas[cma_area_count];
-       if (name) {
-               cma->name = name;
-       } else {
-               cma->name = kasprintf(GFP_KERNEL, "cma%d\n", cma_area_count);
-               if (!cma->name)
-                       return -ENOMEM;
-       }
+
+       if (name)
+               snprintf(cma->name, CMA_MAX_NAME, name);
+       else
+               snprintf(cma->name, CMA_MAX_NAME,  "cma%d\n", cma_area_count);
+
        cma->base_pfn = PFN_DOWN(base);
        cma->count = size >> PAGE_SHIFT;
        cma->order_per_bit = order_per_bit;
diff --git a/mm/cma.h b/mm/cma.h
index 33c0b517733c..27d3f0e9f68f 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -2,6 +2,8 @@
 #ifndef __MM_CMA_H__
 #define __MM_CMA_H__
 
+#define CMA_MAX_NAME 64
+
 struct cma {
        unsigned long   base_pfn;
        unsigned long   count;
@@ -12,7 +14,7 @@ struct cma {
        struct hlist_head mem_head;
        spinlock_t mem_head_lock;
 #endif
-       const char *name;
+       char name[CMA_MAX_NAME];
 };
 
 extern struct cma cma_areas[MAX_CMA_AREAS];
-- 
2.23.0