The patch titled
Subject: mm: fix free page check in zone_watermark_ok()
has been added to the -mm tree. Its filename is
mm-bug-fix-free-page-check-in-zone_watermark_ok.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Minchan Kim <minchan@xxxxxxxxxx>
Subject: mm: fix free page check in zone_watermark_ok()
In __zone_watermark_ok(), free and min are signed long type while
z->lowmem_reserve[classzone_idx] is unsigned long type. So comparision of
them could be wrong due to type conversion to unsigned although free_pages
is minus value.
It could return true instead of false in case of order-0 check so that
kswapd could sleep forever. It means livelock because direct reclaimer
loops forever until kswapd set zone->all_unreclaimable.
Aaditya reported this problem when he test my hotplug patch.
Reported-off-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Tested-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Signed-off-by: Aaditya Kumar <aaditya.kumar@xxxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-bug-fix-free-page-check-in-zone_watermark_ok mm/page_alloc.c
--- a/mm/page_alloc.c~mm-bug-fix-free-page-check-in-zone_watermark_ok
+++ a/mm/page_alloc.c
@@ -1594,6 +1594,7 @@ static bool __zone_watermark_ok(struct z
{
/* free_pages my go negative - that's OK */
long min = mark;
+ long lowmem_reserve = z->lowmem_reserve[classzone_idx];
int o;
free_pages -= (1 << order) - 1;
@@ -1602,7 +1603,7 @@ static bool __zone_watermark_ok(struct z
if (alloc_flags & ALLOC_HARDER)
min -= min / 4;
- if (free_pages <= min + z->lowmem_reserve[classzone_idx])
+ if (free_pages <= min + lowmem_reserve)
return false;
for (o = 0; o < order; o++) {
/* At the next order, this order's pages become unavailable */
_
Subject: Subject: mm: fix free page check in zone_watermark_ok()
Patches currently in -mm which might be from minchan@xxxxxxxxxx are
origin.patch
linux-next.patch
swap-allow-swap-readahead-to-be-merged.patch
documentation-update-how-page-cluster-affects-swap-i-o.patch
mm-compaction-cleanup-on-compaction_deferred.patch
memcg-prevent-oom-with-too-many-dirty-pages.patch
mm-clear-pages_scanned-only-if-draining-a-pcp-adds-pages-to-the-buddy-allocator-again.patch
mm-do-not-use-page_count-without-a-page-pin.patch
mm-clean-up-__count_immobile_pages.patch
vmscan-remove-obsolete-shrink_control-comment.patch
mm-hotplug-correctly-setup-fallback-zonelists-when-creating-new-pgdat.patch
mm-hotplug-correctly-add-new-zone-to-all-other-nodes-zone-lists.patch
mm-hotplug-free-zone-pageset-when-a-zone-becomes-empty.patch
mm-hotplug-mark-memory-hotplug-code-in-page_allocc-as-__meminit.patch
mm-factor-out-memory-isolate-functions.patch
mm-bug-fix-free-page-check-in-zone_watermark_ok.patch
memory-hotplug-fix-kswapd-looping-forever-problem.patch
memory-hotplug-fix-kswapd-looping-forever-problem-fix.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
