diff mbox series

[032/165] mm: cma: fix the name of CMA areas

Message ID 20200812013157.V_PQIH6TB%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/165] percpu: return number of released bytes from pcpu_free_area() | expand

Commit Message

Andrew Morton Aug. 12, 2020, 1:31 a.m. UTC 
From: Barry Song <song.bao.hua@hisilicon.com>
Subject: mm: cma: fix the name of CMA areas

Patch series "mm: fix the names of general cma and hugetlb cma", v2.

The current code of CMA can only work when users pass a const string as
name parameter.  we need to fix the way to handle names in CMA.  On the
other hand, to avoid name conflicts after enabling CMA_DEBUGFS, each
hugetlb should get a different CMA name.


This patch (of 2):

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.

[natechancellor@gmail.com: return cma->name directly in cma_get_name]
  Link: https://github.com/ClangBuiltLinux/linux/issues/1063
  Link: http://lkml.kernel.org/r/20200623015840.621964-1-natechancellor@gmail.com
Link: http://lkml.kernel.org/r/20200616223131.33828-2-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/cma.c |   15 +++++++--------
 mm/cma.h |    4 +++-
 2 files changed, 10 insertions(+), 9 deletions(-)
diff mbox series

Patch

--- a/mm/cma.c~mm-cma-fix-the-name-of-cma-areas
+++ a/mm/cma.c
@@ -52,7 +52,7 @@  unsigned long cma_get_size(const struct
 
 const char *cma_get_name(const struct cma *cma)
 {
-	return cma->name ? cma->name : "(undefined)";
+	return cma->name;
 }
 
 static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
@@ -202,13 +202,12 @@  int __init cma_init_reserved_mem(phys_ad
 	 * 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;
--- a/mm/cma.h~mm-cma-fix-the-name-of-cma-areas
+++ a/mm/cma.h
@@ -4,6 +4,8 @@ 
 
 #include <linux/debugfs.h>
 
+#define CMA_MAX_NAME 64
+
 struct cma {
 	unsigned long   base_pfn;
 	unsigned long   count;
@@ -15,7 +17,7 @@  struct cma {
 	spinlock_t mem_head_lock;
 	struct debugfs_u32_array dfs_bitmap;
 #endif
-	const char *name;
+	char name[CMA_MAX_NAME];
 };
 
 extern struct cma cma_areas[MAX_CMA_AREAS];