On 2025-01-24 13:15:32 [-1000], Tejun Heo wrote: > Hello, > > On Fri, Jan 24, 2025 at 06:46:12PM +0100, Sebastian Andrzej Siewior wrote: > ... > > to avoid holding a global lock during a page fault. The lock drop is > > wrong since the support of renames and not a big burden since the lock > > is no longer global. > > It's still a pretty big lock. Hopefully, at least name accesses can be > converted to rcu protected ones later? Not sure what you mean by "rcu protected ones". The name is already RCU protected which is part of the problem :P Assuming an upper length of name to be around 255 and kernfs_fop_readdir() to be very early on the chain then we could copy the name on stack within the RCU section and do this without ::kernfs_rwsem. > > Don't re-acquire kernfs_root::kernfs_rwsem while copying the name to the > > userpace buffer. > > > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > > Acked-by: Tejun Heo <tj@xxxxxxxxxx> > > Thanks. Sebastian
