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| author | Yu Zhao <yuzhao@google.com> | 2014-10-29 14:50:26 -0700 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-11-13 19:02:55 +0100 |
| commit | ce55507d1cbc4429323efc3f9fafe2ff4c60de49 (patch) | |
| tree | 7c5e3cebe21fe7d11eee93cc22ab84011b6ca95b /mm | |
| parent | b67eae0838424db8b4bb2f49024922df6792d0bb (diff) | |
| download | lwn-ce55507d1cbc4429323efc3f9fafe2ff4c60de49.tar.gz lwn-ce55507d1cbc4429323efc3f9fafe2ff4c60de49.zip | |
mm: free compound page with correct order
commit 5ddacbe92b806cd5b4f8f154e8e46ac267fff55c upstream.
Compound page should be freed by put_page() or free_pages() with correct
order. Not doing so will cause tail pages leaked.
The compound order can be obtained by compound_order() or use
HPAGE_PMD_ORDER in our case. Some people would argue the latter is
faster but I prefer the former which is more general.
This bug was observed not just on our servers (the worst case we saw is
11G leaked on a 48G machine) but also on our workstations running Ubuntu
based distro.
$ cat /proc/vmstat | grep thp_zero_page_alloc
thp_zero_page_alloc 55
thp_zero_page_alloc_failed 0
This means there is (thp_zero_page_alloc - 1) * (2M - 4K) memory leaked.
Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: David Rientjes <rientjes@google.com>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 10532dd43abc..e497843f5f65 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -192,7 +192,7 @@ retry: preempt_disable(); if (cmpxchg(&huge_zero_page, NULL, zero_page)) { preempt_enable(); - __free_page(zero_page); + __free_pages(zero_page, compound_order(zero_page)); goto retry; } @@ -224,7 +224,7 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink, if (atomic_cmpxchg(&huge_zero_refcount, 1, 0) == 1) { struct page *zero_page = xchg(&huge_zero_page, NULL); BUG_ON(zero_page == NULL); - __free_page(zero_page); + __free_pages(zero_page, compound_order(zero_page)); return HPAGE_PMD_NR; } |