From: Yu Kuai <yukuai3@xxxxxxxxxx>
iocost is initialized when it's configured the first time, and iocost
initializing can race with del_gendisk(), which will cause null pointer
dereference:
t1 t2
ioc_qos_write
blk_iocost_init
rq_qos_add
del_gendisk
rq_qos_exit
//iocost is removed from q->roqs
blkcg_activate_policy
pd_init_fn
ioc_pd_init
ioc = q_to_ioc(blkg->q)
//can't find iocost and return null
And iolatency is about to switch to the same lazy initialization.
This patchset fix this problem by synchronize rq_qos_add() and
blkcg_activate_policy() with rq_qos_exit().
Yu Kuai (4):
block/rq_qos: protect 'q->rq_qos' with queue_lock in rq_qos_exit()
block/rq_qos: fail rq_qos_add() after del_gendisk()
blk-cgroup: add a new interface blkcg_conf_close_bdev()
blk-cgroup: synchronize del_gendisk() with configuring cgroup policy
block/blk-cgroup.c | 12 ++++++++++--
block/blk-cgroup.h | 1 +
block/blk-iocost.c | 8 ++++----
block/blk-rq-qos.c | 25 ++++++++++++++++++++-----
block/blk-rq-qos.h | 17 +++++++++++++----
include/linux/blkdev.h | 1 +
6 files changed, 49 insertions(+), 15 deletions(-)
--
2.31.1
