diff options
| author | Jianyu Zhan <nasa4836@gmail.com> | 2014-06-04 16:09:51 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-04 16:54:07 -0700 |
| commit | bea04b073292b2acb522c7c1aa67a4fc58151530 (patch) | |
| tree | 9d4efd221e0fa4b649cc6fbcfa19baa22cb3b3be /mm/rmap.c | |
| parent | e9ade569910a82614ff5f2c2cea2b65a8d785da4 (diff) | |
| download | lwn-bea04b073292b2acb522c7c1aa67a4fc58151530.tar.gz lwn-bea04b073292b2acb522c7c1aa67a4fc58151530.zip | |
mm: use the light version __mod_zone_page_state in mlocked_vma_newpage()
mlocked_vma_newpage() is called with pte lock held(a spinlock), which
implies preemtion disabled, and the vm stat counter is not modified from
interrupt context, so we need not use an irq-safe mod_zone_page_state()
here, using a light-weight version __mod_zone_page_state() would be OK.
This patch also documents __mod_zone_page_state() and some of its
callsites. The comment above __mod_zone_page_state() is from Hugh
Dickins, and acked by Christoph.
Most credits to Hugh and Christoph for the clarification on the usage of
the __mod_zone_page_state().
[akpm@linux-foundation.org: coding-style fixes]
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 8754e1fa83b6..4644e10248f0 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -988,6 +988,12 @@ void do_page_add_anon_rmap(struct page *page, { int first = atomic_inc_and_test(&page->_mapcount); if (first) { + /* + * We use the irq-unsafe __{inc|mod}_zone_page_stat because + * these counters are not modified in interrupt context, and + * pte lock(a spinlock) is held, which implies preemption + * disabled. + */ if (PageTransHuge(page)) __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); @@ -1079,6 +1085,11 @@ void page_remove_rmap(struct page *page) /* * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED * and not charged by memcg for now. + * + * We use the irq-unsafe __{inc|mod}_zone_page_stat because + * these counters are not modified in interrupt context, and + * these counters are not modified in interrupt context, and + * pte lock(a spinlock) is held, which implies preemption disabled. */ if (unlikely(PageHuge(page))) goto out; |