diff options
| author | Yu Zhao <yuzhao@google.com> | 2014-10-30 00:50:26 +0300 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2014-11-13 14:48:55 +0300 |
| commit | 803ea00de36f4293b121ff8be763c6699e4538ae (patch) | |
| tree | bf17e28d4ef2ea82e5a175264494094101abd4cc /mm/huge_memory.c | |
| parent | 9da2bdc4050303cc9c007a408d212b3445edd855 (diff) | |
| download | linux-803ea00de36f4293b121ff8be763c6699e4538ae.tar.xz | |
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: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'mm/huge_memory.c')
| -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 c9ef81e08e4a..ee1ad7886999 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -200,7 +200,7 @@ 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; } @@ -232,7 +232,7 @@ 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; } |