Hi, On 2020/2/19 20:55, Jan Kara wrote:
Hi! On Sat 15-02-20 21:54:08, Yufen Yu wrote:
I've now noticed there's commit 68f23b8906 "memcg: fix a crash in wb_workfn when a device disappears" from end of January which tries to address the issue you're looking into. Now AFAIU the code is till somewhat racy after that commit so I wanted to mention this mostly so that you fixup also the new bdi_dev_name() while you're fixing blkg_dev_name(). Also I was wondering about one thing: If we really care about bdi->dev only for the name, won't we be much better off with just copying the name to bdi->name on registration? Sure it would consume a bit of memory for the name copy but I don't think we really care and things would be IMO *much* simpler that way... Yufen, Tejun, what do you think?
I think copying the name to bdi->name is also need protected by lock. Otherwise, the reader of bdi->name may read incorrect value when re-registion have not copy the name completely. Right? So, I also think using RCU to protect object lifetimes may be a better way. Thanks, Yufen
