Message-ID: <1439823392.10801.16.camel@decadent.org.uk>
Subject: Re: [PATCH] mm: Change global memory state symbols to GPL-only
From: Ben Hutchings <ben@decadent.org.uk>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>
Date: Mon, 17 Aug 2015 16:56:32 +0200
In-Reply-To: <20150817135448.GB10928@dhcp22.suse.cz>
References: <1439682147.10857.99.camel@decadent.org.uk>
	 <20150817135448.GB10928@dhcp22.suse.cz>
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On Mon, 2015-08-17 at 15:54 +0200, Michal Hocko wrote:
> On Sun 16-08-15 01:42:27, Ben Hutchings wrote:
> > Proprietary modules should not be able to touch vm_stat or participate
> > in shrinking.
>=20
> How does the external and !GPL fs does slab reclaim? Those are essential
> for the proper memory balancing.

If they know how to do shrinking on Linux then they are probably
derivative works of Linux.

Ben.

> You are probably right about vm_stat though. Those counters should be
> out of those modules.
>=20
> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > ---
> >  mm/vmscan.c | 4 ++--
> >  mm/vmstat.c | 2 +-
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> >=20
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 8286938..e6e7449 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -247,7 +247,7 @@ int register_shrinker(struct shrinker *shrinker)
> >  > > 	> > up_write(&shrinker_rwsem);
> >  > > 	> > return 0;
> >  }
> > -EXPORT_SYMBOL(register_shrinker);
> > +EXPORT_SYMBOL_GPL(register_shrinker);
> > =20
> >  /*
> >   * Remove one
> > @@ -259,7 +259,7 @@ void unregister_shrinker(struct shrinker *shrinker)
> >  > > 	> > up_write(&shrinker_rwsem);
> >  > > 	> > kfree(shrinker->nr_deferred);
> >  }
> > -EXPORT_SYMBOL(unregister_shrinker);
> > +EXPORT_SYMBOL_GPL(unregister_shrinker);
> > =20
> >  #define SHRINK_BATCH 128
> > =20
> > diff --git a/mm/vmstat.c b/mm/vmstat.c
> > index 4f5cd97..6d3f8f4 100644
> > --- a/mm/vmstat.c
> > +++ b/mm/vmstat.c
> > @@ -87,7 +87,7 @@ void vm_events_fold_cpu(int cpu)
> >   * vm_stat contains the global counters
> >   */
> >  atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_sm=
p;
> > -EXPORT_SYMBOL(vm_stat);
> > +EXPORT_SYMBOL_GPL(vm_stat);
> > =20
> >  #ifdef CONFIG_SMP
> > =20
> > --=20
> > Ben Hutchings
> > [W]e found...that it wasn't as easy to get programs right as we had tho=
ught.
> > ... I realized that a large part of my life from then on was going to b=
e spent
> > in finding mistakes in my own programs. - Maurice Wilkes, 1949
> >=20
>=20
>=20
>=20
--=20
Ben Hutchings
[W]e found...that it wasn't as easy to get programs right as we had thought=
.
... I realized that a large part of my life from then on was going to be sp=
ent
in finding mistakes in my own programs. - Maurice Wilkes, 1949


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