From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: js1304@gmail.com, 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, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2 06/11] mm/slab: don't keep free slabs if free_objects exceeds free_limit
Date: Fri, 22 Jul 2016 20:51:02 +0900 [thread overview]
Message-ID: <2b417127-20a6-ef00-f541-57337a97c9ec@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <1460436666-20462-7-git-send-email-iamjoonsoo.kim@lge.com>
Joonsoo Kim wrote:
> @@ -3313,6 +3310,14 @@ static void free_block(struct kmem_cache *cachep, void **objpp,
> list_add_tail(&page->lru, &n->slabs_partial);
> }
> }
> +
> + while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
> + n->free_objects -= cachep->num;
> +
> + page = list_last_entry(&n->slabs_free, struct page, lru);
> + list_del(&page->lru);
> + list_add(&page->lru, list);
> + }
> }
>
> static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
>
I noticed that kmemcheck complains that n->free_limit is not initialized.
[ 0.000000] Console: colour VGA+ 80x25
[ 0.000000] console [tty0] enabled
[ 0.000000] console [ttyS0] enabled
[ 0.000000] WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff88013ec085b8)
[ 0.000000] a085c03e0188ffffa085c03e0188ffff06000000000000000000000000000000
[ 0.000000] i i i i i i i i i i i i i i i i i i i i i i i i u u u u i i i i
[ 0.000000] ^
[ 0.000000] RIP: 0010:[<ffffffff8113073e>] [<ffffffff8113073e>] free_block+0x14e/0x1d0
[ 0.000000] RSP: 0000:ffffffff81803e58 EFLAGS: 00010046
[ 0.000000] RAX: 0000000000000006 RBX: ffff88013ec0c000 RCX: 0000000000000000
[ 0.000000] RDX: 0000000000000000 RSI: ffff88013f7c5418 RDI: ffff88013ec0c000
[ 0.000000] RBP: ffffffff81803e88 R08: ffffffff81803ea0 R09: ffff88013ec08580
[ 0.000000] R10: ffff88013f7c55d0 R11: 00000000000005cd R12: ffff88013f7c5408
[ 0.000000] R13: ffffffff81803ea0 R14: 0000000002000000 R15: 000000000000001b
[ 0.000000] FS: 0000000000000000(0000) GS:ffffffff8182c000(0000) knlGS:0000000000000000
[ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.000000] CR2: ffff88013e800000 CR3: 000000000180c000 CR4: 00000000000406b0
[ 0.000000] [<ffffffff81131a84>] __do_tune_cpucache+0x84/0x310
[ 0.000000] [<ffffffff81131d35>] do_tune_cpucache+0x25/0x90
[ 0.000000] [<ffffffff81131df0>] enable_cpucache+0x50/0xc0
[ 0.000000] [<ffffffff818b5c70>] kmem_cache_init_late+0x3f/0x68
[ 0.000000] [<ffffffff81895eda>] start_kernel+0x2f2/0x48d
[ 0.000000] [<ffffffff8189553a>] x86_64_start_reservations+0x2f/0x31
[ 0.000000] [<ffffffff81895632>] x86_64_start_kernel+0xf6/0x111
[ 0.000000] [<ffffffffffffffff>] 0xffffffffffffffff
[ 0.000000] tsc: Unable to calibrate against PIT
[ 0.000000] tsc: using PMTIMER reference calibration
[ 0.000000] tsc: Detected 2793.551 MHz processor
Setting 0 at kmem_cache_node_init() fixes the problem, but what the initial
value should be? (Since list_empty(&n->slabs_free) == true, uninitialized
read of n->free_limit does not cause problems except kmemcheck.)
diff --git a/mm/slab.c b/mm/slab.c
index cc6d816..6e0fa8c 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -233,6 +233,7 @@ static void kmem_cache_node_init(struct kmem_cache_node *parent)
spin_lock_init(&parent->list_lock);
parent->free_objects = 0;
parent->free_touched = 0;
+ parent->free_limit = 0;
}
#define MAKE_LIST(cachep, listp, slab, nodeid) \
--
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next prev parent reply other threads:[~2016-07-22 11:52 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 ` [PATCH v2 02/11] mm/slab: remove BAD_ALIEN_MAGIC again js1304
2016-04-12 16:41 ` 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 [this message]
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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