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Message-ID: <alpine.DEB.2.21.1810171315250.6000@nanos.tec.linutronix.de>
Date: Wed, 17 Oct 2018 13:17:18 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Peter Zijlstra <peterz@...radead.org>
cc: David Laight <David.Laight@...LAB.COM>,
'Sebastian Andrzej Siewior' <bigeasy@...utronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"x86@...nel.org" <x86@...nel.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...nel.org>,
Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 1/3] x86/mm/pat: Disable preemption around
__flush_tlb_all()
On Wed, 17 Oct 2018, Peter Zijlstra wrote:
> On Wed, Oct 17, 2018 at 09:54:38AM +0000, David Laight wrote:
> > > * We should perform an IPI and flush all tlbs,
> > > * but that can deadlock->flush only current cpu:
> > > */
> > > + preempt_disable();
> > > __flush_tlb_all();
> > > + preempt_enable();
> >
> > Can it make any sense to flush the tlb with preemption enabled?
> > Surely preemption must be disabled over something else as well?
>
> This code is fishy anyway, for only doing that local invalidate.
>
> Ideally we'd never ever merge anything that only does local invalidates,
> on a global address space, that's just broken.
A little bit late to lament about that.
So should we just replace it with cpa_flush_all() ?
Thanks,
tglx
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