The patch titled
memcg: avoid use cmpxchg in swap cgroup maintainance
has been removed from the -mm tree. Its filename was
memcg-avoid-use-cmpxchg-in-swap-cgroup-maintainance.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: memcg: avoid use cmpxchg in swap cgroup maintainance
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Reported-by: Sachin Sant <sachinp@xxxxxxxxxx> wrote:
Acked-by: Balbir Singh <balbir@xxxxxxxxxx>
Acked-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_cgroup.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff -puN mm/page_cgroup.c~memcg-avoid-use-cmpxchg-in-swap-cgroup-maintainance mm/page_cgroup.c
--- a/mm/page_cgroup.c~memcg-avoid-use-cmpxchg-in-swap-cgroup-maintainance
+++ a/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_e
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_en
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, unsigne
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;
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
origin.patch
memcg-disable-move-charge-in-no-mmu-case.patch
memcontrol-fix-potential-null-deref.patch
linux-next.patch
cgroups-net_cls-as-module.patch
vfs-introduce-fmode_neg_offset-for-allowing-negative-f_pos.patch
memcg-oom-wakeup-filter.patch
memcg-oom-notifier.patch
memcg-oom-notifier-fix.patch
memcg-oom-kill-disable-and-oom-status.patch
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