Re: [External] [PATCH v3] dma-buf: Add DmaBufTotal counter in meminfo

Muchun Song
2021-04-17T03:05:47Z

On Sat, Apr 17, 2021 at 12:08 AM Peter Enderborg
<peter.enderborg@sony.com> wrote:
>
> 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.

I want to know more details about the problems.
Can you share what problems you have encountered?

Thanks.

>
> 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..d40fff2ae1fa 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_get_size - Return the used nr pages by dma-buf
> + */
> +long dma_buf_allocated_pages(void)
> +{
> + return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_allocated_pages);

Why need "EXPORT_SYMBOL_GPL"?

> +
> #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
>