On Mon 20-04-20 09:48:01, Christoph Hellwig wrote: > On Sun, Apr 19, 2020 at 06:06:51PM +0200, Christoph Hellwig wrote: > > > (https://lore.kernel.org/linux-block/20200416071519.807660-4-hch@xxxxxx/) > > > and also to the replies to that patch? This is what I found in the replies: > > > "When driver try to to re-register bdi but without release_bdi(), the old > > > dev_name will be cover directly by the newer in bdi_register_va(). So, I am > > > not sure whether it can cause memory leak for bdi->dev_name." > > > > > > Has it been considered to avoid that leak by freeing bdi->dev_name from > > > unregister_bdi(), e.g. as follows? > > > > We'd need some protection against concurrent accesses as unregister_bdi > > can race with them. But with RCU that could be handled, so let me try > > that. > > I looked into it, and while it seems doable I think this goes in the > wrong direction as it pushed the RCU knowledge into the callers. I'd > rather get something like this series in ASAP, and then for 5.8 or 5.9 > move the bdi pointer to the gendisk and stop re-registering it and thus > solve the problems root cause for real. Yeah, if it could be done it would be a nice solution. Because re-registering of BDIs is a long-term source of troubles... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
