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From: Andi Kleen <ak@linux.intel.com>
To: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	 Tim Chen <tim.c.chen@linux.intel.com>,
	 Arjan van de Ven <arjan@linux.intel.com>,
	 LKML <linux-kernel@vger.kernel.org>,
	 KarimAllah Ahmed <karahmed@amazon.de>,
	 Andrea Arcangeli <aarcange@redhat.com>,
	 Ashok Raj <ashok.raj@intel.com>,
	 Asit Mallick <asit.k.mallick@intel.com>,
	 Borislav Petkov <bp@suse.de>,
	 Dan Williams <dan.j.williams@intel.com>,
	 Dave Hansen <dave.hansen@intel.com>,
	 David Woodhouse <dwmw@amazon.co.uk>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	 "H . Peter Anvin" <hpa@zytor.com>,
	 Ingo Molnar <mingo@redhat.com>,
	 Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
	 Joerg Roedel <joro@8bytes.org>,
	 Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [RFC PATCH 1/2] x86/ibpb: Skip IBPB when we switch back to same user process
Date: Thu, 25 Jan 2018 13:57:49 -0800	[thread overview]
Message-ID: <87h8r9k3du.fsf@linux.intel.com> (raw)
In-Reply-To: <CALCETrUGDeHse24sOygh5EcsXuZHPtZnw3adhzADfn+yKgcOzg@mail.gmail.com> (Andy Lutomirski's message of "Thu, 25 Jan 2018 13:04:23 -0800")

Andy Lutomirski <luto@kernel.org> writes:
>
> That being said, just stashing last_user_mm without any refcounting
> should be fine.

If last_user_mm is freed and reallocated by a different process,
then that would miss the IPBP incorrectly.

-Andi

  reply	other threads:[~2018-01-25 21:57 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-25  0:36 [RFC PATCH 1/2] x86/ibpb: Skip IBPB when we switch back to same user process Tim Chen
2018-01-25  0:36 ` [RFC PATCH 2/2] x86/ibpb: Prevent missed IBPB flush Tim Chen
2018-01-25  8:20   ` David Woodhouse
2018-01-25 16:56     ` Tim Chen
2018-01-25  8:58 ` [RFC PATCH 1/2] x86/ibpb: Skip IBPB when we switch back to same user process Peter Zijlstra
2018-01-25  9:22   ` Peter Zijlstra
2018-01-25 13:21     ` Arjan van de Ven
2018-01-25 13:50       ` Peter Zijlstra
2018-01-25 14:07         ` Arjan van de Ven
2018-01-25 16:41           ` Peter Zijlstra
2018-01-25 17:04             ` Andy Lutomirski
2018-01-25 18:18               ` Peter Zijlstra
2018-01-25 19:32                 ` Tim Chen
2018-01-25 19:34                   ` Arjan van de Ven
2018-01-25 19:45                     ` Dave Hansen
2018-01-25 20:46                   ` Peter Zijlstra
2018-01-25 21:04                     ` Andy Lutomirski
2018-01-25 21:57                       ` Andi Kleen [this message]
2018-01-25 22:01                         ` Andy Lutomirski
2018-01-25 23:07                           ` Tim Chen
2018-01-26  0:01                       ` Peter Zijlstra
2018-01-25 17:24             ` Arjan van de Ven

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