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| author | Arun KS <arunks@codeaurora.org> | 2018-12-28 00:34:24 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:47 -0800 |
| commit | 9705bea5f833f4fc21d5bef5fce7348427f76ea4 (patch) | |
| tree | 37604aa5b680736eb176283f970e1c1d7d27bbf3 /include | |
| parent | 3d6357de8aa09e1966770dc1171c72679946464f (diff) | |
| download | linux-9705bea5f833f4fc21d5bef5fce7348427f76ea4.tar.gz linux-9705bea5f833f4fc21d5bef5fce7348427f76ea4.tar.bz2 linux-9705bea5f833f4fc21d5bef5fce7348427f76ea4.zip | |
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 'include')
| -rw-r--r-- | include/linux/mmzone.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 077d797d1f60..a23e34e21178 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -435,7 +435,7 @@ struct zone { * adjust_managed_page_count() should be used instead of directly * touching zone->managed_pages and totalram_pages. */ - unsigned long managed_pages; + atomic_long_t managed_pages; unsigned long spanned_pages; unsigned long present_pages; @@ -524,6 +524,11 @@ enum pgdat_flags { PGDAT_RECLAIM_LOCKED, /* prevents concurrent reclaim */ }; +static inline unsigned long zone_managed_pages(struct zone *zone) +{ + return (unsigned long)atomic_long_read(&zone->managed_pages); +} + static inline unsigned long zone_end_pfn(const struct zone *zone) { return zone->zone_start_pfn + zone->spanned_pages; @@ -820,7 +825,7 @@ static inline bool is_dev_zone(const struct zone *zone) */ static inline bool managed_zone(struct zone *zone) { - return zone->managed_pages; + return zone_managed_pages(zone); } /* Returns true if a zone has memory */ |