mm: convert totalram_pages and totalhigh_pages variables to atomic

totalram_pages and totalhigh_pages are made static inline function.

Main motivation was that managed_page_count_lock handling was complicating
things.  It was discussed in length here,
https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes
better to remove the lock and convert variables to atomic, with preventing
poteintial store-to-read tearing as a bonus.

[akpm@linux-foundation.org: coding style fixes]
Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
Suggested-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/mm/highmem.c b/mm/highmem.c
index 59db3223a5d6..107b10f9878e 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -105,9 +105,8 @@ static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
 }
 #endif
 
-unsigned long totalhigh_pages __read_mostly;
-EXPORT_SYMBOL(totalhigh_pages);
-
+atomic_long_t _totalhigh_pages __read_mostly;
+EXPORT_SYMBOL(_totalhigh_pages);
 
 EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);