> 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?
>
Can't we detect it via list_empty(&sb->s_shrink.list) test
before calling register_shrinker_prepared(&sb->s_shrink) ?
