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authorYu Zhao <yuzhao@google.com>2014-10-29 14:50:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-29 16:33:14 -0700
commit5ddacbe92b806cd5b4f8f154e8e46ac267fff55c (patch)
tree45394bb991b7403f73ce540ce9add87fa874f350
parentf601de204465048bdf0d5537f630729622ebc3a6 (diff)
mm: free compound page with correct order
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> Cc: <stable@vger.kernel.org> [3.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/huge_memory.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 74c78aa8bc2f..780d12c000e9 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;
}