On Wed, Dec 20, 2023 at 01:27:51PM +0800, Changbin Du wrote:
> On Tue, Dec 19, 2023 at 01:52:03PM -0800, Luis Chamberlain wrote:
> > On Tue, Dec 19, 2023 at 12:51:51PM -0800, Andrew Morton wrote:
> > > On Tue, 19 Dec 2023 22:12:31 +0800 Changbin Du <changbin.du@xxxxxxxxxx> wrote:
> > >
> > > > The commit 1a7b7d922081 ("modules: Use vmalloc special flag") moves
> > > > do_free_init() into a global workqueue instead of call_rcu(). So now
> > > > we should wait it via flush_work().
> > >
> > > What are the runtime effects of this change?
> >
> > Indeed that's needed given how old this culprit commit is:
> >
> > git describe --contains 1a7b7d922081
> > v5.2-rc1~192^2~5
> >
> > Who did this work and for what reason? What triggered this itch?
> >
> Seems the waiting was introduced by commit ae646f0b9ca ("init: fix false positives
> in W+X checking").
>
> As what I have observed, mark_readonly() is only invoked by the first user mode
> thread function kernel_init(), which is before userspace /init. So is it real
> possible we have loaded modules at this point?
Are you saying we don't free any module inits at all then? I asked a lot
of questions and your answers seem slim.
How did you find this?
What actual impact does this have without the patch?
The commit must document this.
Luis
