summaryrefslogtreecommitdiff
path: root/mm/page_alloc.c
diff options
context:
space:
mode:
authorVlastimil Babka <vbabka@suse.cz>2016-10-07 16:57:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-07 18:46:27 -0700
commit984fdba6a32e4e9819ebc06ca3acec6582ffd99f (patch)
tree03b39654e09b114e15decd406436f28ecd87d102 /mm/page_alloc.c
parent9861a62c335cd34a2b6b25aaaf5898e8370299ec (diff)
mm, compaction: use proper alloc_flags in __compaction_suitable()
The __compaction_suitable() function checks the low watermark plus a compact_gap() gap to decide if there's enough free memory to perform compaction. This check uses direct compactor's alloc_flags, but that's wrong, since these flags are not applicable for freepage isolation. For example, alloc_flags may indicate access to memory reserves, making compaction proceed, and then fail watermark check during the isolation. A similar problem exists for ALLOC_CMA, which may be part of alloc_flags, but not during freepage isolation. In this case however it makes sense to use ALLOC_CMA both in __compaction_suitable() and __isolate_free_page(), since there's actually nothing preventing the freepage scanner to isolate from CMA pageblocks, with the assumption that a page that could be migrated once by compaction can be migrated also later by CMA allocation. Thus we should count pages in CMA pageblocks when considering compaction suitability and when isolating freepages. To sum up, this patch should remove some false positives from __compaction_suitable(), and allow compaction to proceed when free pages required for compaction reside in the CMA pageblocks. Link: http://lkml.kernel.org/r/20160810091226.6709-10-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a2214c64ed3c..637b0e907df0 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2491,7 +2491,7 @@ int __isolate_free_page(struct page *page, unsigned int order)
if (!is_migrate_isolate(mt)) {
/* Obey watermarks as if the page was being allocated */
watermark = low_wmark_pages(zone) + (1 << order);
- if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+ if (!zone_watermark_ok(zone, 0, watermark, 0, ALLOC_CMA))
return 0;
__mod_zone_freepage_state(zone, -(1UL << order), mt);