[PATCH] dmabuf: Add the capability to expose DMA-BUF stats in sysfs

[Greg KH]

On Wed, Dec 09, 2020 at 08:43:57PM -0800, Hridya Valsaraju wrote:
> This patch allows statistics to be enabled for each DMA-BUF in
> sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS.
> 
> The following stats will be exposed by the interface:
> 
> /sys/kernel/dmabuf/<inode_number>/exporter_name
> /sys/kernel/dmabuf/<inode_number>/size
> /sys/kernel/dmabuf/<inode_number>/dev_map_info
> 
> The inode_number is unique for each DMA-BUF and was added earlier [1]
> in order to allow userspace to track DMA-BUF usage across different
> processes.
> 
> Currently, this information is exposed in
> /sys/kernel/debug/dma_buf/bufinfo.
> However, since debugfs is considered unsafe to be mounted in production,
> it is being duplicated in sysfs.
> 
> This information is intended to help with root-causing
> low-memory kills and the debugging/analysis of other memory-related issues.
> 
> It will also be used to derive DMA-BUF
> per-exporter stats and per-device usage stats for Android Bug reports.
> 
> [1]: https://lore.kernel.org/patchwork/patch/1088791/
> 
> Signed-off-by: Hridya Valsaraju <hridya at google.com>

Thanks for adding all of this, nice work!

Reviewed-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>