Provides a userspace interface to trigger a CMA release.
Usage:
echo [pages] > free
This would provide testing/fuzzing access to the CMA release paths.
Signed-off-by: Sasha Levin <sasha.le...@oracle.com>
---
mm/cma_debug.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index 39c7116..0a63945 100644
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -11,6 +11,7 @@
#include <linux/kernel.h>
#include <linux/dma-contiguous.h>
#include <linux/slab.h>
+#include <linux/mm_types.h>
#include "cma.h"
@@ -43,6 +44,56 @@ static void cma_add_to_cma_mem_list(struct cma_mem *mem)
spin_unlock(&cma_mem_head_lock);
}
+static struct cma_mem *cma_get_entry_from_list(void)
+{
+ struct cma_mem *mem = NULL;
+
+ spin_lock(&cma_mem_head_lock);
+ if (!hlist_empty(&cma_mem_head)) {
+ mem = hlist_entry(cma_mem_head.first, struct cma_mem, node);
+ hlist_del_init(&mem->node);
+ }
+ spin_unlock(&cma_mem_head_lock);
+
+ return mem;
+}
+
+static int cma_free_mem(struct cma *cma, int count)
+{
+ struct cma_mem *mem = NULL;
+
+ while (count) {
+ mem = cma_get_entry_from_list();
+ if (mem == NULL)
+ return 0;
+
+ if (mem->n <= count) {
+ cma_release(cma, mem->p, mem->n);
+ count -= mem->n;
+ kfree(mem);
+ } else {
+ cma_release(cma, mem->p, count);
+ mem->p += count;
+ mem->n -= count;
+ count = 0;
+ cma_add_to_cma_mem_list(mem);
+ }
+ }
+
+ return 0;
+
+}
+
+static int cma_free_write(void *data, u64 val)
+{
+ int pages = val;
+ struct cma *cma = data;
+
+ return cma_free_mem(cma, pages);
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(cma_free_fops, NULL, cma_free_write, "%llu\n");
+
static int cma_alloc_mem(struct cma *cma, int count)
{
struct cma_mem *mem;
@@ -89,6 +140,9 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
debugfs_create_file("alloc", S_IWUSR, cma_debugfs_root, cma,
&cma_alloc_fops);
+ debugfs_create_file("free", S_IWUSR, cma_debugfs_root, cma,
+ &cma_free_fops);
+
debugfs_create_file("base_pfn", S_IRUGO, tmp,
&cma->base_pfn, &cma_debugfs_fops);
debugfs_create_file("count", S_IRUGO, tmp,
--
1.7.10.4
--
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