On 01/17/2018 10:57 AM, Ming Lei wrote: > Hi Jianchao, > > On Wed, Jan 17, 2018 at 04:09:11PM +0800, jianchao.wang wrote: >> Hi ming >> >> Thanks for your kindly response. >> >> On 01/17/2018 02:22 PM, Ming Lei wrote: >>> This warning can't be removed completely, for example, the CPU figured >>> in blk_mq_hctx_next_cpu(hctx) can be put on again just after the >>> following call returns and before __blk_mq_run_hw_queue() is scheduled >>> to run. >>> >>> kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work, msecs_to_jiffies(msecs)) >> We could use cpu_active in __blk_mq_run_hw_queue() to narrow the window. >> There is a big gap between cpu_online and cpu_active. rebind_workers is also between them. > > This warning is harmless, also you can't reproduce it without help of your > special patch, I guess, :-) So the window shouldn't be a big deal. FWIW, every WARN_ON is problematic since there are people running with panic_on_warn. If a condition can happen we should not use WARN_ON but something else.
