Date:   Tue, 31 Jan 2023 11:02:27 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
Cc:     Petr Mladek <pmladek@suse.com>,
        Joe Lawrence <joe.lawrence@redhat.com>, kvm@vger.kernel.org,
        "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org,
        Jiri Kosina <jikos@kernel.org>, linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        "Seth Forshee (DigitalOcean)" <sforshee@digitalocean.com>,
        live-patching@vger.kernel.org, Miroslav Benes <mbenes@suse.cz>
Subject: Re: [PATCH 0/2] vhost: improve livepatch switching for heavily
 loaded vhost worker kthreads
Message-ID: <Y9jnM6BW5CcKjXNv@hirez.programming.kicks-ass.net>
References: <20230120-vhost-klp-switching-v1-0-7c2b65519c43@kernel.org>
 <Y9KyVKQk3eH+RRse@alley>
 <Y9LswwnPAf+nOVFG@do-x1extreme>
 <20230127044355.frggdswx424kd5dq@treble>
 <Y9OpTtqWjAkC2pal@hirez.programming.kicks-ass.net>
 <20230127165236.rjcp6jm6csdta6z3@treble>
 <20230127170946.zey6xbr4sm4kvh3x@treble>
 <20230127221131.sdneyrlxxhc4h3fa@treble>
 <Y9e6ssSHUt+MUvum@hirez.programming.kicks-ass.net>
 <20230130195930.s5iu76e56j4q5bra@treble>
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On Mon, Jan 30, 2023 at 11:59:30AM -0800, Josh Poimboeuf wrote:

> @@ -8662,16 +8665,19 @@ void sched_dynamic_update(int mode)
>  
>  	switch (mode) {
>  	case preempt_dynamic_none:
> -		preempt_dynamic_enable(cond_resched);
> +		if (!klp_override)
> +			preempt_dynamic_enable(cond_resched);
>  		preempt_dynamic_disable(might_resched);
>  		preempt_dynamic_disable(preempt_schedule);
>  		preempt_dynamic_disable(preempt_schedule_notrace);
>  		preempt_dynamic_disable(irqentry_exit_cond_resched);
> +		//FIXME avoid printk for klp restore

		if (mode != preempt_dynamic_mode)

>  		pr_info("Dynamic Preempt: none\n");
>  		break;
>  
>  	case preempt_dynamic_voluntary:
> -		preempt_dynamic_enable(cond_resched);
> +		if (!klp_override)
> +			preempt_dynamic_enable(cond_resched);
>  		preempt_dynamic_enable(might_resched);
>  		preempt_dynamic_disable(preempt_schedule);
>  		preempt_dynamic_disable(preempt_schedule_notrace);