Re: [PATCH] mm: Change global memory state symbols to GPL-only

[Michal Hocko]

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.

How does the external and !GPL fs does slab reclaim? Those are essential
for the proper memory balancing.

You are probably right about vm_stat though. Those counters should be
out of those modules.

> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
> ---
>  mm/vmscan.c | 4 ++--
>  mm/vmstat.c | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> 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);
>  
>  /*
>   * 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);
>  
>  #define SHRINK_BATCH 128
>  
> 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_smp;
> -EXPORT_SYMBOL(vm_stat);
> +EXPORT_SYMBOL_GPL(vm_stat);
>  
>  #ifdef CONFIG_SMP
>  
> -- 
> 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 spent
> in finding mistakes in my own programs. - Maurice Wilkes, 1949
> 



-- 
Michal Hocko
SUSE Labs
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