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From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Laight <David.Laight@ACULAB.COM>,
	'Sebastian Andrzej Siewior' <bigeasy@linutronix.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH 1/3] x86/mm/pat: Disable preemption around __flush_tlb_all()
Date: Wed, 17 Oct 2018 13:17:18 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1810171315250.6000@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20181017111145.GJ3121@hirez.programming.kicks-ass.net>

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

  reply	other threads:[~2018-10-17 11:17 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-16 20:25 [0/3] A few 32bit x86 fixes Sebastian Andrzej Siewior
2018-10-16 20:25 ` [PATCH 1/3] x86/mm/pat: Disable preemption around __flush_tlb_all() Sebastian Andrzej Siewior
2018-10-16 21:25   ` Andy Lutomirski
2018-10-16 21:38     ` Sebastian Andrzej Siewior
2018-10-16 23:28       ` Andy Lutomirski
2018-10-17 10:34         ` [PATCH 1/3 v2] " Sebastian Andrzej Siewior
2018-10-29 18:10           ` [tip:x86/urgent] " tip-bot for Sebastian Andrzej Siewior
2018-11-05 21:56             ` Dan Williams
2018-10-17  9:54   ` [PATCH 1/3] " David Laight
2018-10-17 10:39     ` 'Sebastian Andrzej Siewior'
2018-10-17 11:45       ` David Laight
2018-10-17 12:00         ` 'Sebastian Andrzej Siewior'
2018-10-17 11:11     ` Peter Zijlstra
2018-10-17 11:17       ` Thomas Gleixner [this message]
2018-10-17 15:47         ` Peter Zijlstra
2018-10-17 15:55           ` Thomas Gleixner
2018-10-17 16:00           ` 'Sebastian Andrzej Siewior'
2018-10-17 16:22             ` Peter Zijlstra
2018-10-16 20:25 ` [PATCH 2/3] x86/fpu: Remove second definition of fpu in __fpu__restore_sig() Sebastian Andrzej Siewior
2018-10-16 21:26   ` Andy Lutomirski
2018-10-17  9:09   ` [tip:x86/urgent] " tip-bot for Sebastian Andrzej Siewior
2018-10-18  6:22   ` tip-bot for Sebastian Andrzej Siewior
2018-10-16 20:25 ` [PATCH 3/3] x86/fpu: Save FPU registers on context switch if there is a FPU Sebastian Andrzej Siewior
2018-10-16 23:00   ` Andy Lutomirski
2018-10-17  9:10   ` [tip:x86/urgent] x86/fpu: Fix i486 + no387 boot crash by only saving FPU registers on context switch if there is an FPU tip-bot for Sebastian Andrzej Siewior
2018-10-18  6:22   ` tip-bot for Sebastian Andrzej Siewior

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