Messages in this thread | | | Date | Tue, 19 Jul 2022 15:50:32 +0800 | Subject | Re: [PATCH] block: don't allow the same type rq_qos add more than once | From | hanjinke <> |
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Thanks for your review. I have saw this review just after the send of patch v2
在 2022/7/19 下午2:53, Muchun Song 写道: > On Mon, Jul 18, 2022 at 4:37 PM Jinke Han <hanjinke.666@bytedance.com> wrote: >> >> From: hanjinke <hanjinke.666@bytedance.com> >> >> In our test of iocost, we encounttered some list add/del corrutions of >> inner_walk list in ioc_timer_fn. >> The resean can be descripted as follow: >> >> cpu 0 cpu 1 >> ioc_qos_write ioc_qos_write >> >> ioc = q_to_ioc(bdev_get_queue(bdev)); >> if (!ioc) { >> ioc = kzalloc(); ioc = q_to_ioc(bdev_get_queue(bdev)); >> if (!ioc) { >> ioc = kzalloc(); >> ... >> rq_qos_add(q, rqos); >> } >> ... >> rq_qos_add(q, rqos); >> ... >> } >> >> When the io.cost.qos file is written by two cpu 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 ioc have the >> same root iocg, the root iocg's walk_list may be overwritten by each >> other and this lead to list add/del corrutions in building or destorying >> 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: hanjinke <hanjinke.666@bytedance.com> > > The change LGTM. Maybe it is better to add a Fixes tag here so that > others can easily know what Linux versions should be backported. > > Reviewed-by: Muchun Song <songmuchun@bytedance.com> > > Thanks.
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