[RFC PATCH 2/2] block/cfq: Fix memory leak of async cfqq

From: Jeffy Chen
Date: Sat Sep 30 2017 - 04:14:54 EST


Currently we only unref the async cfqqs in cfq_pd_offline, which would
not be called when CONFIG_CFQ_GROUP_IOSCHED is disabled.

Kmemleak reported:
unreferenced object 0xffffffc0cd9fc000 (size 240):
comm "kworker/3:1", pid 52, jiffies 4294673527 (age 97.149s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 80 55 13 cf c0 ff ff ff .........U......
10 c0 9f cd c0 ff ff ff 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffff9008c6f720>] kmemleak_alloc+0x58/0x8c
[<ffffff900828f87c>] kmem_cache_alloc+0x184/0x268
[<ffffff90084ce300>] cfq_get_queue.isra.11+0x144/0x2e0
[<ffffff90084ce8b0>] cfq_set_request+0x1bc/0x444
[<ffffff9008495730>] elv_set_request+0x88/0x9c
[<ffffff900849d690>] get_request+0x494/0x914
[<ffffff900849de34>] blk_get_request+0xdc/0x160
[<ffffff90086e8054>] scsi_execute+0x70/0x23c
[<ffffff90086e8314>] scsi_test_unit_ready+0xf4/0x1ec

Signed-off-by: Jeffy Chen <jeffy.chen@xxxxxxxxxxxxxx>
---

block/cfq-iosched.c | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9f342ef1ad42..75773eabecc7 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -401,6 +401,7 @@ struct cfq_data {

static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
static void cfq_put_queue(struct cfq_queue *cfqq);
+static void cfqg_offline(struct cfq_group *cfqg);

static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
enum wl_class_t class,
@@ -1638,17 +1639,8 @@ static void cfq_pd_init(struct blkg_policy_data *pd)
static void cfq_pd_offline(struct blkg_policy_data *pd)
{
struct cfq_group *cfqg = pd_to_cfqg(pd);
- int i;
-
- for (i = 0; i < IOPRIO_BE_NR; i++) {
- if (cfqg->async_cfqq[0][i])
- cfq_put_queue(cfqg->async_cfqq[0][i]);
- if (cfqg->async_cfqq[1][i])
- cfq_put_queue(cfqg->async_cfqq[1][i]);
- }

- if (cfqg->async_idle_cfqq)
- cfq_put_queue(cfqg->async_idle_cfqq);
+ cfqg_offline(cfqg);

/*
* @blkg is going offline and will be ignored by
@@ -3741,6 +3733,21 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfqq->pid = pid;
}

+static void cfqg_offline(struct cfq_group *cfqg)
+{
+ int i;
+
+ for (i = 0; i < IOPRIO_BE_NR; i++) {
+ if (cfqg->async_cfqq[0][i])
+ cfq_put_queue(cfqg->async_cfqq[0][i]);
+ if (cfqg->async_cfqq[1][i])
+ cfq_put_queue(cfqg->async_cfqq[1][i]);
+ }
+
+ if (cfqg->async_idle_cfqq)
+ cfq_put_queue(cfqg->async_idle_cfqq);
+}
+
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
{
@@ -4564,6 +4571,7 @@ static void cfq_exit_queue(struct elevator_queue *e)
#ifdef CONFIG_CFQ_GROUP_IOSCHED
blkcg_deactivate_policy(q, &blkcg_policy_cfq);
#else
+ cfqg_offline(cfqd->root_group);
kfree(cfqd->root_group);
#endif
kfree(cfqd);
--
2.11.0