non-atomic rss_stat modifications

[Dave Jones <davej@redhat.com>]

I've been trying to make sense of this message which I keep seeing..

BUG: Bad rss-counter state mm:ffff88018bb78000 idx:0 val:1

Looking at the FILEPAGES counter accesses...

$ rgrep FILEPAGES mm
mm/filemap_xip.c:			dec_mm_counter(mm, MM_FILEPAGES);
mm/oom_kill.c:		K(get_mm_counter(victim->mm, MM_FILEPAGES)));
mm/fremap.c:			dec_mm_counter(mm, MM_FILEPAGES);
mm/memory.c:					rss[MM_FILEPAGES]++;
mm/memory.c:			rss[MM_FILEPAGES]++;
mm/memory.c:				rss[MM_FILEPAGES]--;
mm/memory.c:					rss[MM_FILEPAGES]--;
mm/memory.c:	inc_mm_counter_fast(mm, MM_FILEPAGES);
mm/memory.c:				dec_mm_counter_fast(mm, MM_FILEPAGES);
mm/memory.c:			inc_mm_counter_fast(mm, MM_FILEPAGES);
mm/rmap.c:				dec_mm_counter(mm, MM_FILEPAGES);
mm/rmap.c:		dec_mm_counter(mm, MM_FILEPAGES);
mm/rmap.c:		dec_mm_counter(mm, MM_FILEPAGES);


How come we sometimes use the atomic accessors, but in copy_one_pte() and
zap_pte_range() we don't ?  Is that safe ?

	Dave

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