diff options
| author | Arun KS <arunks@codeaurora.org> | 2018-12-28 00:34:20 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:47 -0800 |
| commit | 3d6357de8aa09e1966770dc1171c72679946464f (patch) | |
| tree | a24bb2f8795ea4927c1ff64d5f5f00398bee925d /drivers/hv | |
| parent | fecd4a50baaebf6bde7f9e0b88fef13ffe5d98a1 (diff) | |
mm: reference totalram_pages and managed_pages once per function
Patch series "mm: convert totalram_pages, totalhigh_pages and managed
pages to atomic", v5.
This series converts totalram_pages, totalhigh_pages and
zone->managed_pages to atomic variables.
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.
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 It seemes better
to remove the lock and convert variables to atomic. With the change,
preventing poteintial store-to-read tearing comes as a bonus.
This patch (of 4):
This is in preparation to a later patch which converts totalram_pages and
zone->managed_pages to atomic variables. Please note that re-reading the
value might lead to a different value and as such it could lead to
unexpected behavior. There are no known bugs as a result of the current
code but it is better to prevent from them in principle.
Link: http://lkml.kernel.org/r/1542090790-21750-2-git-send-email-arunks@codeaurora.org
Signed-off-by: Arun KS <arunks@codeaurora.org>
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 'drivers/hv')
| -rw-r--r-- | drivers/hv/hv_balloon.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c index 41631512ae97..f3e7da981610 100644 --- a/drivers/hv/hv_balloon.c +++ b/drivers/hv/hv_balloon.c @@ -1090,6 +1090,7 @@ static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg) static unsigned long compute_balloon_floor(void) { unsigned long min_pages; + unsigned long nr_pages = totalram_pages; #define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) /* Simple continuous piecewiese linear function: * max MiB -> min MiB gradient @@ -1102,16 +1103,16 @@ static unsigned long compute_balloon_floor(void) * 8192 744 (1/16) * 32768 1512 (1/32) */ - if (totalram_pages < MB2PAGES(128)) - min_pages = MB2PAGES(8) + (totalram_pages >> 1); - else if (totalram_pages < MB2PAGES(512)) - min_pages = MB2PAGES(40) + (totalram_pages >> 2); - else if (totalram_pages < MB2PAGES(2048)) - min_pages = MB2PAGES(104) + (totalram_pages >> 3); - else if (totalram_pages < MB2PAGES(8192)) - min_pages = MB2PAGES(232) + (totalram_pages >> 4); + if (nr_pages < MB2PAGES(128)) + min_pages = MB2PAGES(8) + (nr_pages >> 1); + else if (nr_pages < MB2PAGES(512)) + min_pages = MB2PAGES(40) + (nr_pages >> 2); + else if (nr_pages < MB2PAGES(2048)) + min_pages = MB2PAGES(104) + (nr_pages >> 3); + else if (nr_pages < MB2PAGES(8192)) + min_pages = MB2PAGES(232) + (nr_pages >> 4); else - min_pages = MB2PAGES(488) + (totalram_pages >> 5); + min_pages = MB2PAGES(488) + (nr_pages >> 5); #undef MB2PAGES return min_pages; } |