The patch titled
Subject: mm/swap_slots.c: remove lock_initialized flag from swap_slots_cache
has been added to the -mm tree. Its filename is
mm-swap-remove-lock_initialized-flag-from-swap_slots_cache.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-swap-remove-lock_initialized-flag-from-swap_slots_cache.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-swap-remove-lock_initialized-flag-from-swap_slots_cache.patch
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------------------------------------------------------
From: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Subject: mm/swap_slots.c: remove lock_initialized flag from swap_slots_cache
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.
Link: http://lkml.kernel.org/r/867d1fb070644e6d5f0ac7780f63e75259b82cc3.1500677066.git.tim.c.chen@xxxxxxxxxxxxxxx
Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Reported-by: Wenwei Tao <wenwei.tww@xxxxxxxxxxxxxxx>
Cc: Ying Huang <ying.huang@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/swap_slots.h | 1 -
mm/swap_slots.c | 9 ++++-----
2 files changed, 4 insertions(+), 6 deletions(-)
diff -puN include/linux/swap_slots.h~mm-swap-remove-lock_initialized-flag-from-swap_slots_cache include/linux/swap_slots.h
--- a/include/linux/swap_slots.h~mm-swap-remove-lock_initialized-flag-from-swap_slots_cache
+++ a/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 -puN mm/swap_slots.c~mm-swap-remove-lock_initialized-flag-from-swap_slots_cache mm/swap_slots.c
--- a/mm/swap_slots.c~mm-swap-remove-lock_initialized-flag-from-swap_slots_cache
+++ a/mm/swap_slots.c
@@ -140,11 +140,10 @@ static int alloc_swap_slot_cache(unsigne
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;
_
Patches currently in -mm which might be from tim.c.chen@xxxxxxxxxxxxxxx are
mm-swap-fix-race-conditions-in-swap_slots-cache-init.patch
mm-swap-remove-lock_initialized-flag-from-swap_slots_cache.patch
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