From: "H. Peter Anvin" <hpa@zytor.com>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86-64, espfix: consider IRQs are off when initializing
Date: Thu, 17 Jul 2014 09:16:11 -0700 [thread overview]
Message-ID: <53C7F6CB.4070606@zytor.com> (raw)
In-Reply-To: <53C7F2B2.2000803@oracle.com>
On 07/17/2014 08:58 AM, Sasha Levin wrote:
>
> This is the result of getting an error message for allocating with GFP_KERNEL
> saying that we can't do that with IRQs off.
>
> My assumption after that was that we're not going to be sleeping at all, which
> is why spinlock/GFP_ATOMIC would be correct here.
>
So we have a problem, but the proposed solution is wrong. This is
messy... we need this code to be successfully executed before we can
safely schedule *user space* on that processor, but there is no
requirement that we execute it before we enable *interrupts* on that
processor, so maybe there is a way we can fulfill those requirements.
The alternative would be to fail to enable the processor or going into a
spin loop, but either of those would been rather toxic to me.
-hpa
prev parent reply other threads:[~2014-07-17 16:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-17 15:13 [PATCH] x86-64, espfix: consider IRQs are off when initializing Sasha Levin
2014-07-17 15:48 ` H. Peter Anvin
2014-07-17 15:58 ` Sasha Levin
2014-07-17 16:16 ` H. Peter Anvin [this message]
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