From: Rik van Riel <riel@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Borislav Petkov <bp@suse.de>,
Andy Lutomirski <luto@kernel.org>, Mel Gorman <mgorman@suse.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] x86/mm: disable preemption during CR3 read+write
Date: Fri, 05 Aug 2016 10:38:33 -0400 [thread overview]
Message-ID: <1470407913.13905.66.camel@redhat.com> (raw)
In-Reply-To: <1470404259-26290-1-git-send-email-bigeasy@linutronix.de>
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On Fri, 2016-08-05 at 15:37 +0200, Sebastian Andrzej Siewior wrote:
>
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -135,7 +135,14 @@ static inline void
> cr4_set_bits_and_update_boot(unsigned long mask)
>
> static inline void __native_flush_tlb(void)
> {
> + /*
> + * if current->mm == NULL then we borrow a mm which may
> change during a
> + * task switch and therefore we must not be preempted while
> we write CR3
> + * back.
> + */
> + preempt_disable();
> native_write_cr3(native_read_cr3());
> + preempt_enable();
> }
That is one subtle race!
Acked-by: Rik van Riel <riel@redhat.com>
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All Rights Reversed.
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next prev parent reply other threads:[~2016-08-05 14:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-05 13:37 [PATCH] x86/mm: disable preemption during CR3 read+write Sebastian Andrzej Siewior
2016-08-05 13:37 ` Sebastian Andrzej Siewior
2016-08-05 13:53 ` Peter Zijlstra
2016-08-05 13:53 ` Peter Zijlstra
2016-08-05 14:38 ` Rik van Riel [this message]
2016-08-05 15:42 ` Andy Lutomirski
2016-08-05 15:42 ` Andy Lutomirski
2016-08-05 15:52 ` Sebastian Andrzej Siewior
2016-08-05 15:52 ` Sebastian Andrzej Siewior
2016-08-10 18:10 ` [tip:x86/urgent] x86/mm: Disable " tip-bot for Sebastian Andrzej Siewior
2017-10-17 15:57 [PATCH] " Sebastian Andrzej Siewior
2017-10-18 15:01 ` Bernhard Kaindl
2017-10-18 16:51 ` Greg KH
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