[PATCH v5] dma-buf: Add DmaBufTotal counter in meminfo

Peter Enderborg
2021-04-17T16:40:34Z

This adds a total used dma-buf memory. Details
can be found in debugfs, however it is not for everyone
and not always available. dma-buf are indirect allocated by
userspace. So with this value we can monitor and detect
userspace applications that have problems.

Signed-off-by: Peter Enderborg <peter.enderborg@sony.com>
---
drivers/dma-buf/dma-buf.c | 12 ++++++++++++
fs/proc/meminfo.c | 5 ++++-
include/linux/dma-buf.h | 1 +
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f264b70c383e..4dc37cd4293b 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -37,6 +37,7 @@ struct dma_buf_list {
};

static struct dma_buf_list db_list;
+static atomic_long_t dma_buf_global_allocated;

static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
{
@@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry)
if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
dma_resv_fini(dmabuf->resv);

+ atomic_long_sub(dmabuf->size, &dma_buf_global_allocated);
module_put(dmabuf->owner);
kfree(dmabuf->name);
kfree(dmabuf);
@@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
mutex_lock(&db_list.lock);
list_add(&dmabuf->list_node, &db_list.head);
mutex_unlock(&db_list.lock);
+ atomic_long_add(dmabuf->size, &dma_buf_global_allocated);

return dmabuf;

@@ -1346,6 +1349,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
}
EXPORT_SYMBOL_GPL(dma_buf_vunmap);

+/**
+ * dma_buf_allocated_pages - Return the used nr of pages
+ * allocated for dma-buf
+ */
+long dma_buf_allocated_pages(void)
+{
+ return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT;
+}
+
#ifdef CONFIG_DEBUG_FS
static int dma_buf_debug_show(struct seq_file *s, void *unused)
{
diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
index 6fa761c9cc78..ccc7c40c8db7 100644
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -16,6 +16,7 @@
#ifdef CONFIG_CMA
#include <linux/cma.h>
#endif
+#include <linux/dma-buf.h>
#include <asm/page.h>
#include "internal.h"

@@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
show_val_kb(m, "CmaFree: ",
global_zone_page_state(NR_FREE_CMA_PAGES));
#endif
-
+#ifdef CONFIG_DMA_SHARED_BUFFER
+ show_val_kb(m, "DmaBufTotal: ", dma_buf_allocated_pages());
+#endif
hugetlb_report_meminfo(m);

arch_report_meminfo(m);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index efdc56b9d95f..5b05816bd2cd 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
unsigned long);
int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
+long dma_buf_allocated_pages(void);
#endif /* __DMA_BUF_H__ */
--
2.17.1