On Wed 22-04-20 09:38:46, Christoph Hellwig wrote:
> Cache a copy of the name for the life time of the backing_dev_info
> structure so that we can reference it even after unregistering.
>
> Fixes: 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears")
> Reported-by: Yufen Yu <yuyufen@xxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> include/linux/backing-dev-defs.h | 1 +
> mm/backing-dev.c | 5 +++--
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
> index 4fc87dee005a..2849bdbb3acb 100644
> --- a/include/linux/backing-dev-defs.h
> +++ b/include/linux/backing-dev-defs.h
> @@ -220,6 +220,7 @@ struct backing_dev_info {
> wait_queue_head_t wb_waitq;
>
> struct device *dev;
> + char dev_name[64];
> struct device *owner;
>
> struct timer_list laptop_mode_wb_timer;
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index c2c44c89ee5d..efc5b83acd2d 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -938,7 +938,8 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
> if (bdi->dev) /* The driver needs to use separate queues per device */
> return 0;
>
> - dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
> + vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
> + dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
> if (IS_ERR(dev))
> return PTR_ERR(dev);
>
> @@ -1047,7 +1048,7 @@ const char *bdi_dev_name(struct backing_dev_info *bdi)
> {
> if (!bdi || !bdi->dev)
> return bdi_unknown_name;
> - return dev_name(bdi->dev);
> + return bdi->dev_name;
> }
> EXPORT_SYMBOL_GPL(bdi_dev_name);
>
> --
> 2.26.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
