Subject: Re: [PATCH] mm: memcontrol: only manage socket pressure for CONFIG_INET

From: Andrew Morton <akpm-de/[email-masked]>
Date: Wed, 9 Dec 2015 14:28:36 -0800

On Wed, 9 Dec 2015 13:58:58 -0500 Johannes Weiner <[email-masked]> wrote:

> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 6faea81e66d7..73cd572167bb 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -4220,13 +4220,13 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
> >  	if (ret)
> >  		return ret;
> >  
> > +#ifdef CONFIG_INET
> >  #ifdef CONFIG_MEMCG_LEGACY_KMEM
> >  	ret = tcp_init_cgroup(memcg);
> >  	if (ret)
> >  		return ret;
> >  #endif
> 
> The calls to tcp_init_cgroup() appear earlier in the series than "mm:
> memcontrol: hook up vmpressure to socket pressure". However, they get
> moved around a few times so fixing it earlier means respinning the
> series. Andrew, it's up to you whether we take the bisectability hit
> for !CONFIG_INET && CONFIG_MEMCG (how common is this?) or whether you
> want me to resend the series.

hm, drat, I was suspecting dependency issues here, but a test build
said it was OK.

Actually, I was expecting this patch series to depend on the linux-next
cgroup2 changes, but that doesn't appear to be the case.  *should* this
series be staged after the cgroup2 code?

Regarding this particular series: yes, I think we can live with a
bisection hole for !CONFIG_INET && CONFIG_MEMCG users.  But I'm not
sure why we're discussing bisection issues, because Arnd's build
failure occurs with everything applied?

> Sorry about the trouble. I don't have a git tree on kernel.org because
> we don't really use git in -mm, but the downside is that we don't get
> the benefits of the automatic build testing for all kinds of configs.
> I'll try to set up a git tree to expose series to full build coverage
> before they hit -mm and -next.

This sort of thing happens quite rarely.