Re: [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head

On 1/23/21 1:10 PM, Sebastian Andrzej Siewior wrote:

Patch 2+3 were applied and then dropped by Jens due to a NOHZ+softirq
related warning [0]. Turns out a successful wakeup via
set_nr_if_polling() will not process any softirqs and the CPU may go
back to idle. This is addressed by patch #1.

smpcfd_dying_cpu() will also invoke SMP-functions calls via
flush_smp_call_function_queue() but the block layer shouldn't queue
anything because the CPU isn't online anymore.
The two caller of flush_smp_call_function_from_idle() look fine with
opening interrupts from within do_softirq().

[0] https://lkml.kernel.org/r/1ee4b31b-350e-a9f5-4349-cfb34b89829a@kernel.dk

I can queue up the block side once the IPI fix is in some stable branch
that I can pull in.

-- 
Jens Axboe