On Tue, May 15, 2018 at 09:27:35AM +0900, Tetsuo Handa wrote: > Eric Biggers wrote: > > > I'm not following, since generic_shutdown_super() only calls ->put_super() if > > > ->s_root is set, which only happens at the end of shmem_fill_super(). Isn't the > > > real problem that s_shrink is registered too early, causing super_cache_count() > > > and shmem_unused_huge_count() to potentially run before shmem_fill_super() has > > > completed? Or alternatively, the problem is that super_cache_count() doesn't > > > check for SB_ACTIVE. > > > > > > > Coincidentally, this is already going to be fixed by commit 79f546a696bff259 > > ("fs: don't scan the inode cache before SB_BORN is set") in vfs/for-linus. > > > > Just an idea, but if shrinker registration is too early, can't we postpone it > like below? Wonderful. And when ->mount() returns you a subtree of the same filesystem again, that will do what, exactly?