From: Tim Chen <tim.c.chen@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
Ying Huang <ying.huang@intel.com>,
Wenwei Tao <wenwei.tww@alibaba-inc.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Hillf Danton <hillf.zj@alibaba-inc.com>
Subject: [PATCH 2/2] mm/swap: Remove lock_initialized flag from swap_slots_cache
Date: Fri, 21 Jul 2017 15:45:01 -0700 [thread overview]
Message-ID: <867d1fb070644e6d5f0ac7780f63e75259b82cc3.1500677066.git.tim.c.chen@linux.intel.com> (raw)
In-Reply-To: <65a9d0f133f63e66bba37b53b2fd0464b7cae771.1500677066.git.tim.c.chen@linux.intel.com>
In-Reply-To: <65a9d0f133f63e66bba37b53b2fd0464b7cae771.1500677066.git.tim.c.chen@linux.intel.com>
We will only reach the lock initialization code
in alloc_swap_slot_cache when the cpu's swap_slots_cache's slots
have not been allocated and swap_slots_cache has not been initialized
previously. So the lock_initialized check is redundant and unnecessary.
Remove lock_initialized flag from swap_slots_cache to save memory.
Reported-by: Wenwei Tao <wenwei.tww@alibaba-inc.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
include/linux/swap_slots.h | 1 -
mm/swap_slots.c | 9 ++++-----
2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/include/linux/swap_slots.h b/include/linux/swap_slots.h
index 6ef92d1..a75c30b 100644
--- a/include/linux/swap_slots.h
+++ b/include/linux/swap_slots.h
@@ -10,7 +10,6 @@
#define THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE (2*SWAP_SLOTS_CACHE_SIZE)
struct swap_slots_cache {
- bool lock_initialized;
struct mutex alloc_lock; /* protects slots, nr, cur */
swp_entry_t *slots;
int nr;
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 4c5457c..c039e6c 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -140,11 +140,10 @@ static int alloc_swap_slot_cache(unsigned int cpu)
if (cache->slots || cache->slots_ret)
/* cache already allocated */
goto out;
- if (!cache->lock_initialized) {
- mutex_init(&cache->alloc_lock);
- spin_lock_init(&cache->free_lock);
- cache->lock_initialized = true;
- }
+
+ mutex_init(&cache->alloc_lock);
+ spin_lock_init(&cache->free_lock);
+
cache->nr = 0;
cache->cur = 0;
cache->n_ret = 0;
--
2.9.4
--
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next prev parent reply other threads:[~2017-07-21 22:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-21 22:45 [PATCH 1/2] mm/swap: Fix race conditions in swap_slots cache init Tim Chen
2017-07-21 22:45 ` Tim Chen [this message]
2017-07-24 2:15 ` [PATCH 2/2] mm/swap: Remove lock_initialized flag from swap_slots_cache Huang, Ying
2017-07-24 16:54 ` Tim Chen
2017-10-03 22:27 ` [PATCH 1/2] mm/swap: Fix race conditions in swap_slots cache init Andrew Morton
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