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Subject[PATCH] memcg: move page-freeing code out of lock
Date
Move page-freeing code out of swap_cgroup_mutex in the hope that it
could reduce few of theoretical contentions between swapons and/or
swapoffs.

This is just a cleanup, no functional changes.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: containers@lists.linux-foundation.org
---
mm/page_cgroup.c | 22 +++++++++++++---------
1 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 29951abc852e..17eb5eb95bab 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -463,8 +463,8 @@ int swap_cgroup_swapon(int type, unsigned long max_pages)
/* memory shortage */
ctrl->map = NULL;
ctrl->length = 0;
- vfree(array);
mutex_unlock(&swap_cgroup_mutex);
+ vfree(array);
goto nomem;
}
mutex_unlock(&swap_cgroup_mutex);
@@ -479,7 +479,8 @@ nomem:

void swap_cgroup_swapoff(int type)
{
- int i;
+ struct page **map;
+ unsigned long i, length;
struct swap_cgroup_ctrl *ctrl;

if (!do_swap_account)
@@ -487,17 +488,20 @@ void swap_cgroup_swapoff(int type)

mutex_lock(&swap_cgroup_mutex);
ctrl = &swap_cgroup_ctrl[type];
- if (ctrl->map) {
- for (i = 0; i < ctrl->length; i++) {
- struct page *page = ctrl->map[i];
+ map = ctrl->map;
+ length = ctrl->length;
+ ctrl->map = NULL;
+ ctrl->length = 0;
+ mutex_unlock(&swap_cgroup_mutex);
+
+ if (map) {
+ for (i = 0; i < length; i++) {
+ struct page *page = map[i];
if (page)
__free_page(page);
}
- vfree(ctrl->map);
- ctrl->map = NULL;
- ctrl->length = 0;
+ vfree(map);
}
- mutex_unlock(&swap_cgroup_mutex);
}

#endif
--
1.7.4


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