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authorArun KS <arunks@codeaurora.org>2018-12-28 11:34:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-28 23:11:47 +0300
commit9705bea5f833f4fc21d5bef5fce7348427f76ea4 (patch)
tree37604aa5b680736eb176283f970e1c1d7d27bbf3 /mm/vmstat.c
parent3d6357de8aa09e1966770dc1171c72679946464f (diff)
downloadlinux-9705bea5f833f4fc21d5bef5fce7348427f76ea4.tar.xz
mm: convert zone->managed_pages to atomic variable
totalram_pages, zone->managed_pages and totalhigh_pages updates are protected by managed_page_count_lock, but readers never care about it. Convert these variables to atomic to avoid readers potentially seeing a store tear. This patch converts zone->managed_pages. Subsequent patches will convert totalram_panges, totalhigh_pages and eventually managed_page_count_lock will be removed. 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. Link: http://lkml.kernel.org/r/1542090790-21750-3-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: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/vmstat.c')
-rw-r--r--mm/vmstat.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 9c624595e904..83b30edc2f7f 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -227,7 +227,7 @@ int calculate_normal_threshold(struct zone *zone)
* 125 1024 10 16-32 GB 9
*/
- mem = zone->managed_pages >> (27 - PAGE_SHIFT);
+ mem = zone_managed_pages(zone) >> (27 - PAGE_SHIFT);
threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
@@ -1569,7 +1569,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
high_wmark_pages(zone),
zone->spanned_pages,
zone->present_pages,
- zone->managed_pages);
+ zone_managed_pages(zone));
seq_printf(m,
"\n protection: (%ld",