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authorJinke Han <hanjinke.666@bytedance.com>2022-07-20 12:36:16 +0300
committerJens Axboe <axboe@kernel.dk>2022-07-20 15:44:14 +0300
commit14a6e2eb7df5c7897c15b109cba29ab0c4a791b6 (patch)
treecdd54c468148f2449898595522e500995046ad5f /block/blk-wbt.c
parentbf14fad19ffbb3d37a1bb1324f966973e7d4a7b6 (diff)
downloadlinux-14a6e2eb7df5c7897c15b109cba29ab0c4a791b6.tar.xz
block: don't allow the same type rq_qos add more than once
In our test of iocost, we encountered some list add/del corruptions of inner_walk list in ioc_timer_fn. The reason can be described as follows: cpu 0 cpu 1 ioc_qos_write ioc_qos_write ioc = q_to_ioc(queue); if (!ioc) { ioc = kzalloc(); ioc = q_to_ioc(queue); if (!ioc) { ioc = kzalloc(); ... rq_qos_add(q, rqos); } ... rq_qos_add(q, rqos); ... } When the io.cost.qos file is written by two cpus concurrently, rq_qos may be added to one disk twice. In that case, there will be two iocs enabled and running on one disk. They own different iocgs on their active list. In the ioc_timer_fn function, because of the iocgs from two iocs have the same root iocg, the root iocg's walk_list may be overwritten by each other and this leads to list add/del corruptions in building or destroying the inner_walk list. And so far, the blk-rq-qos framework works in case that one instance for one type rq_qos per queue by default. This patch make this explicit and also fix the crash above. Signed-off-by: Jinke Han <hanjinke.666@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20220720093616.70584-1-hanjinke.666@bytedance.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-wbt.c')
-rw-r--r--block/blk-wbt.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index f2e4bf1dca47..a9982000b667 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -820,6 +820,7 @@ int wbt_init(struct request_queue *q)
{
struct rq_wb *rwb;
int i;
+ int ret;
rwb = kzalloc(sizeof(*rwb), GFP_KERNEL);
if (!rwb)
@@ -846,7 +847,10 @@ int wbt_init(struct request_queue *q)
/*
* Assign rwb and add the stats callback.
*/
- rq_qos_add(q, &rwb->rqos);
+ ret = rq_qos_add(q, &rwb->rqos);
+ if (ret)
+ goto err_free;
+
blk_stat_add_callback(q, rwb->cb);
rwb->min_lat_nsec = wbt_default_latency_nsec(q);
@@ -855,4 +859,10 @@ int wbt_init(struct request_queue *q)
wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
return 0;
+
+err_free:
+ blk_stat_free_callback(rwb->cb);
+ kfree(rwb);
+ return ret;
+
}