diff options
| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2010-03-15 00:34:57 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-17 18:43:47 -0700 |
| commit | e9e58a4ec3b1086d1ed8c915311aef1ae55454fd (patch) | |
| tree | a500ec01cce13fa17f2400ac57f4ad36f4d37bca | |
| parent | a3d3203e4bb40f253b1541e310dc0f9305be7c84 (diff) | |
memcg: avoid use cmpxchg in swap cgroup maintainance
swap_cgroup uses 2bytes data and uses cmpxchg in a new operation. 2byte
cmpxchg/xchg is not available on some archs. This patch replaces
cmpxchg/xchg with operations under lock.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reported-by: Sachin Sant <sachinp@in.ibm.com> wrote:
Acked-by: Balbir Singh <balbir@in.ibm.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/page_cgroup.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index 3dd88539a0e..6c0081441a3 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -284,6 +284,7 @@ static DEFINE_MUTEX(swap_cgroup_mutex); struct swap_cgroup_ctrl { struct page **map; unsigned long length; + spinlock_t lock; }; struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES]; @@ -353,16 +354,22 @@ unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, struct swap_cgroup_ctrl *ctrl; struct page *mappage; struct swap_cgroup *sc; + unsigned long flags; + unsigned short retval; ctrl = &swap_cgroup_ctrl[type]; mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - if (cmpxchg(&sc->id, old, new) == old) - return old; + spin_lock_irqsave(&ctrl->lock, flags); + retval = sc->id; + if (retval == old) + sc->id = new; else - return 0; + retval = 0; + spin_unlock_irqrestore(&ctrl->lock, flags); + return retval; } /** @@ -383,13 +390,17 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) struct page *mappage; struct swap_cgroup *sc; unsigned short old; + unsigned long flags; ctrl = &swap_cgroup_ctrl[type]; mappage = ctrl->map[idx]; sc = page_address(mappage); sc += pos; - old = xchg(&sc->id, id); + spin_lock_irqsave(&ctrl->lock, flags); + old = sc->id; + sc->id = id; + spin_unlock_irqrestore(&ctrl->lock, flags); return old; } @@ -441,6 +452,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages) mutex_lock(&swap_cgroup_mutex); ctrl->length = length; ctrl->map = array; + spin_lock_init(&ctrl->lock); if (swap_cgroup_prepare(type)) { /* memory shortage */ ctrl->map = NULL; |