On 12/29/2015 09:46 PM, Kirill A. Shutemov wrote:
I missed clear_page_mlock() in page_remove_anon_compound_rmap().
It usually shouldn't cause any problems since we munlock pages
explicitly, but in conjunction with missed munlock in __oom_reap_vmas()
it causes problems:
http://lkml.kernel.org/r/5661FBB6.6050307@xxxxxxxxxx
Let's put it in place an mirror behaviour for small pages.
NOTE: I'm not entirely sure why we ever need clear_page_mlock() in
page_remove_rmap() codepath. It looks redundant to me as we munlock
pages anyway. But this is out of scope of the patch.
Git blame actually quickly points to commit e6c509f854550 which explains
it :)
The patch can be folded into
"thp: allow mlocked THP again"
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Ack.
Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
mm/rmap.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/rmap.c b/mm/rmap.c
index 384516fb7495..68af2e32f7ed 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1356,6 +1356,9 @@ static void page_remove_anon_compound_rmap(struct page *page)
nr = HPAGE_PMD_NR;
}
+ if (unlikely(PageMlocked(page)))
+ clear_page_mlock(page);
+
if (nr) {
__mod_zone_page_state(page_zone(page), NR_ANON_PAGES, -nr);
deferred_split_huge_page(page);
--
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