2014-10-23 14:33:10

by Johannes Weiner

Subject: [patch] mm: memcontrol: inline memcg->move_lock locking

The wrappers around taking and dropping the memcg->move_lock spinlock
add nothing of value. Inline the spinlock calls into the callsites.

Signed-off-by: Johannes Weiner <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
---
mm/memcontrol.c | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 09fece0eb9f1..a5c9aa4688e8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1522,23 +1522,6 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
return false;
}

-/*
- * Take this lock when
- * - a code tries to modify page's memcg while it's USED.
- * - a code tries to modify page state accounting in a memcg.
- */
-static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
- unsigned long *flags)
-{
- spin_lock_irqsave(&memcg->move_lock, *flags);
-}
-
-static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
- unsigned long *flags)
-{
- spin_unlock_irqrestore(&memcg->move_lock, *flags);
-}
-
#define K(x) ((x) << (PAGE_SHIFT-10))
/**
* mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
@@ -2156,9 +2139,9 @@ again:
if (atomic_read(&memcg->moving_account) <= 0)
return memcg;

- move_lock_mem_cgroup(memcg, flags);
+ spin_lock_irqsave(&memcg->move_lock, *flags);
if (memcg != pc->mem_cgroup) {
- move_unlock_mem_cgroup(memcg, flags);
+ spin_unlock_irqrestore(&memcg->move_lock, *flags);
goto again;
}
*locked = true;
@@ -2176,7 +2159,7 @@ void mem_cgroup_end_page_stat(struct mem_cgroup *memcg, bool locked,
unsigned long flags)
{
if (memcg && locked)
- move_unlock_mem_cgroup(memcg, &flags);
+ spin_unlock_irqrestore(&memcg->move_lock, flags);

rcu_read_unlock();
}
@@ -3219,7 +3202,7 @@ static int mem_cgroup_move_account(struct page *page,
if (pc->mem_cgroup != from)
goto out_unlock;

- move_lock_mem_cgroup(from, &flags);
+ spin_lock_irqsave(&from->move_lock, flags);

if (!PageAnon(page) && page_mapped(page)) {
__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
@@ -3243,7 +3226,8 @@ static int mem_cgroup_move_account(struct page *page,

/* caller should have done css_get */
pc->mem_cgroup = to;
- move_unlock_mem_cgroup(from, &flags);
+ spin_unlock_irqrestore(&from->move_lock, flags);
+
ret = 0;

local_irq_disable();
--
2.1.2

2014-10-23 15:09:51

by Michal Hocko

Subject: Re: [patch] mm: memcontrol: inline memcg->move_lock locking

On Thu 23-10-14 10:33:02, Johannes Weiner wrote:
> The wrappers around taking and dropping the memcg->move_lock spinlock
> add nothing of value. Inline the spinlock calls into the callsites.
>
> Signed-off-by: Johannes Weiner <[email protected]>
> Acked-by: Vladimir Davydov <[email protected]>

Acked-by: Michal Hocko <[email protected]>

> ---
> mm/memcontrol.c | 28 ++++++----------------------
> 1 file changed, 6 insertions(+), 22 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 09fece0eb9f1..a5c9aa4688e8 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1522,23 +1522,6 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
> return false;
> }
>
> -/*
> - * Take this lock when
> - * - a code tries to modify page's memcg while it's USED.
> - * - a code tries to modify page state accounting in a memcg.
> - */
> -static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
> - unsigned long *flags)
> -{
> - spin_lock_irqsave(&memcg->move_lock, *flags);
> -}
> -
> -static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
> - unsigned long *flags)
> -{
> - spin_unlock_irqrestore(&memcg->move_lock, *flags);
> -}
> -
> #define K(x) ((x) << (PAGE_SHIFT-10))
> /**
> * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
> @@ -2156,9 +2139,9 @@ again:
> if (atomic_read(&memcg->moving_account) <= 0)
> return memcg;
>
> - move_lock_mem_cgroup(memcg, flags);
> + spin_lock_irqsave(&memcg->move_lock, *flags);
> if (memcg != pc->mem_cgroup) {
> - move_unlock_mem_cgroup(memcg, flags);
> + spin_unlock_irqrestore(&memcg->move_lock, *flags);
> goto again;
> }
> *locked = true;
> @@ -2176,7 +2159,7 @@ void mem_cgroup_end_page_stat(struct mem_cgroup *memcg, bool locked,
> unsigned long flags)
> {
> if (memcg && locked)
> - move_unlock_mem_cgroup(memcg, &flags);
> + spin_unlock_irqrestore(&memcg->move_lock, flags);
>
> rcu_read_unlock();
> }
> @@ -3219,7 +3202,7 @@ static int mem_cgroup_move_account(struct page *page,
> if (pc->mem_cgroup != from)
> goto out_unlock;
>
> - move_lock_mem_cgroup(from, &flags);
> + spin_lock_irqsave(&from->move_lock, flags);
>
> if (!PageAnon(page) && page_mapped(page)) {
> __this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
> @@ -3243,7 +3226,8 @@ static int mem_cgroup_move_account(struct page *page,
>
> /* caller should have done css_get */
> pc->mem_cgroup = to;
> - move_unlock_mem_cgroup(from, &flags);
> + spin_unlock_irqrestore(&from->move_lock, flags);
> +
> ret = 0;
>
> local_irq_disable();
> --
> 2.1.2
>

--
Michal Hocko
SUSE Labs