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From: Jens Axboe <axboe@kernel.dk>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head
Date: Sun, 24 Jan 2021 21:27:54 -0700	[thread overview]
Message-ID: <4e703284-2f75-6030-f697-aa2d362c3949@kernel.dk> (raw)
In-Reply-To: <20210123201027.3262800-1-bigeasy@linutronix.de>

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


  parent reply	other threads:[~2021-01-25  4:29 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-23 20:10 [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head Sebastian Andrzej Siewior
2021-01-23 20:10 ` [PATCH 1/3] smp: Process pending softirqs in flush_smp_call_function_from_idle() Sebastian Andrzej Siewior
2021-02-01 19:35   ` Sebastian Andrzej Siewior
2021-02-09 10:02   ` Peter Zijlstra
2021-02-09 11:35     ` Sebastian Andrzej Siewior
2021-02-10 13:53   ` [tip: sched/core] " tip-bot2 for Sebastian Andrzej Siewior
2021-02-17 13:17   ` tip-bot2 for Sebastian Andrzej Siewior
2021-01-23 20:10 ` [PATCH 2/3] blk-mq: Always complete remote completions requests in softirq Sebastian Andrzej Siewior
2021-01-25  7:10   ` Hannes Reinecke
2021-01-25  8:25     ` Christoph Hellwig
2021-01-25  8:30       ` Sebastian Andrzej Siewior
2021-01-25  8:32         ` Christoph Hellwig
2021-01-25  9:29           ` Sebastian Andrzej Siewior
2021-01-25  8:22   ` Christoph Hellwig
2021-01-25  8:49     ` Christoph Hellwig
2021-01-27 11:22   ` Daniel Wagner
2021-01-23 20:10 ` [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done Sebastian Andrzej Siewior
2021-01-25  8:30   ` Christoph Hellwig
2021-01-25  8:32     ` Sebastian Andrzej Siewior
2021-01-25  8:39       ` Christoph Hellwig
2021-01-25  9:54         ` [PATCH 3/3 v2] " Sebastian Andrzej Siewior
2021-01-25 10:14           ` Christoph Hellwig
2021-01-27 11:23           ` Daniel Wagner
2021-01-25  4:27 ` Jens Axboe [this message]
2021-02-10 14:43 ` [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head Jens Axboe

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