From: Christoph Hellwig hch@lst.de
[ Upstream commit 6bd87eec23cbc9ed222bed0f5b5b02bf300e9a8d ]
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@huawei.com Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 07e02d6df5ad..65d47522413c 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -197,6 +197,7 @@ 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 8501b033bca8..1d37c80d023a 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -880,7 +880,8 @@ 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);
@@ -980,7 +981,7 @@ 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);