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From: js1304@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: [PATCH v2 02/11] mm/slab: remove BAD_ALIEN_MAGIC again
Date: Tue, 12 Apr 2016 13:50:57 +0900	[thread overview]
Message-ID: <1460436666-20462-3-git-send-email-iamjoonsoo.kim@lge.com> (raw)
In-Reply-To: <1460436666-20462-1-git-send-email-iamjoonsoo.kim@lge.com>

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by 'commit
edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")' because it causes
a problem on m68k which has many node but !CONFIG_NUMA.  In this case,
although alien cache isn't used at all but to cope with some
initialization path, garbage value is used and that is BAD_ALIEN_MAGIC.
Now, this patch set use_alien_caches to 0 when !CONFIG_NUMA, there is no
initialization path problem so we don't need BAD_ALIEN_MAGIC at all.  So
remove it.

Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 mm/slab.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index d8746c0..373b8be 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -421,8 +421,6 @@ static struct kmem_cache kmem_cache_boot = {
 	.name = "kmem_cache",
 };
 
-#define BAD_ALIEN_MAGIC 0x01020304ul
-
 static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
 
 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -637,7 +635,7 @@ static int transfer_objects(struct array_cache *to,
 static inline struct alien_cache **alloc_alien_cache(int node,
 						int limit, gfp_t gfp)
 {
-	return (struct alien_cache **)BAD_ALIEN_MAGIC;
+	return NULL;
 }
 
 static inline void free_alien_cache(struct alien_cache **ac_ptr)
@@ -1205,7 +1203,7 @@ void __init kmem_cache_init(void)
 					sizeof(struct rcu_head));
 	kmem_cache = &kmem_cache_boot;
 
-	if (num_possible_nodes() == 1)
+	if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
 		use_alien_caches = 0;
 
 	for (i = 0; i < NUM_INIT_LISTS; i++)
-- 
1.9.1

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  parent reply	other threads:[~2016-04-12  4:51 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-12  4:50 [PATCH v2 00/11] mm/slab: reduce lock contention in alloc path js1304
2016-04-12  4:50 ` [PATCH v2 01/11] mm/slab: fix the theoretical race by holding proper lock js1304
2016-04-12 16:38   ` Christoph Lameter
2016-04-14  1:56     ` Joonsoo Kim
2016-04-12  4:50 ` js1304 [this message]
2016-04-12 16:41   ` [PATCH v2 02/11] mm/slab: remove BAD_ALIEN_MAGIC again Christoph Lameter
2016-04-12  4:50 ` [PATCH v2 03/11] mm/slab: drain the free slab as much as possible js1304
2016-04-12  4:50 ` [PATCH v2 04/11] mm/slab: factor out kmem_cache_node initialization code js1304
2016-04-12 16:53   ` Christoph Lameter
2016-04-26  0:47   ` Joonsoo Kim
2016-04-12  4:51 ` [PATCH v2 05/11] mm/slab: clean-up kmem_cache_node setup js1304
2016-04-12 16:55   ` Christoph Lameter
2016-04-12  4:51 ` [PATCH v2 06/11] mm/slab: don't keep free slabs if free_objects exceeds free_limit js1304
2016-07-22 11:51   ` Tetsuo Handa
2016-07-26  7:18     ` Joonsoo Kim
2016-04-12  4:51 ` [PATCH v2 07/11] mm/slab: racy access/modify the slab color js1304
2016-04-12  4:51 ` [PATCH v2 08/11] mm/slab: make cache_grow() handle the page allocated on arbitrary node js1304
2016-04-12  4:51 ` [PATCH v2 09/11] mm/slab: separate cache_grow() to two parts js1304
2016-04-12  4:51 ` [PATCH v2 10/11] mm/slab: refill cpu cache through a new slab without holding a node lock js1304
2016-04-12  4:51 ` [PATCH v2 11/11] mm/slab: lockless decision to grow cache js1304
2016-04-12  7:24   ` Jesper Dangaard Brouer
2016-04-12  8:16     ` Joonsoo Kim

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