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| author | David Rientjes <rientjes@google.com> | 2012-10-08 16:34:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 16:23:02 +0900 |
| commit | b676b293fb48672904ee1b9828cb50b4eed01717 (patch) | |
| tree | 22b2dcc1623da40a5ddfaf6db2bc5ab1c2476ddb /include/linux/huge_mm.h | |
| parent | e90bdb7f52f94204c78fb40b0804645defdebd71 (diff) | |
| download | lwn-b676b293fb48672904ee1b9828cb50b4eed01717.tar.gz lwn-b676b293fb48672904ee1b9828cb50b4eed01717.zip | |
mm, thp: fix mapped pages avoiding unevictable list on mlock
When a transparent hugepage is mapped and it is included in an mlock()
range, follow_page() incorrectly avoids setting the page's mlock bit and
moving it to the unevictable lru.
This is evident if you try to mlock(), munlock(), and then mlock() a
range again. Currently:
#define MAP_SIZE (4 << 30) /* 4GB */
void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
mlock(ptr, MAP_SIZE);
$ grep -E "Unevictable|Inactive\(anon" /proc/meminfo
Inactive(anon): 6304 kB
Unevictable: 4213924 kB
munlock(ptr, MAP_SIZE);
Inactive(anon): 4186252 kB
Unevictable: 19652 kB
mlock(ptr, MAP_SIZE);
Inactive(anon): 4198556 kB
Unevictable: 21684 kB
Notice that less than 2MB was added to the unevictable list; this is
because these pages in the range are not transparent hugepages since the
4GB range was allocated with mmap() and has no specific alignment. If
posix_memalign() were used instead, unevictable would not have grown at
all on the second mlock().
The fix is to call mlock_vma_page() so that the mlock bit is set and the
page is added to the unevictable list. With this patch:
mlock(ptr, MAP_SIZE);
Inactive(anon): 4056 kB
Unevictable: 4213940 kB
munlock(ptr, MAP_SIZE);
Inactive(anon): 4198268 kB
Unevictable: 19636 kB
mlock(ptr, MAP_SIZE);
Inactive(anon): 4008 kB
Unevictable: 4213940 kB
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/huge_mm.h')
| -rw-r--r-- | include/linux/huge_mm.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 6ab47af5a849..b31cb7da0346 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -11,7 +11,7 @@ extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long address, pmd_t *pmd, pmd_t orig_pmd); -extern struct page *follow_trans_huge_pmd(struct mm_struct *mm, +extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, unsigned int flags); |