linux-kernel - Re: [PATCH V1] x86, espfix: postpone the initialization of espfix stack for AP

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Message-ID: <5581E27F.5060800@zytor.com>
Date:	Wed, 17 Jun 2015 14:11:27 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...en8.de>
CC:	Gu Zheng <guz.fnst@...fujitsu.com>, Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	X86 ML <x86@...nel.org>
Subject: Re: [PATCH V1] x86, espfix: postpone the initialization of espfix
 stack for AP

On 06/17/2015 02:04 PM, Borislav Petkov wrote:
>>
>> It isn't *at all* obvious to me at least that if the GFP_KERNEL
>> allocation fails we may not get rescheduled on another CPU and/or get stuck.
>>
>> I'm starting to think that the right thing to do is to allocate these on
>> the CPU that is bringing up the other CPU, at the same time we allocate
>> the percpu area.  This won't affect offline CPUs.
> 
> Btw, as part of experimenting for something else, I was able to trigger
> this even on a guest here. It is an insane guest though: 16 NUMA nodes,
> with 8 cores each:
> 

Is this reliable?

	-hpa

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