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Message-ID: <4e9e864856fc165b5dea8119eade871bc0e6f019.camel@linux.ibm.com>
Subject: Re: [PATCH v5 00/11] Introduces new count-based method for tracking
 lockless pagetable walks
From:   Leonardo Bras <leonardo@linux.ibm.com>
To:     John Hubbard <jhubbard@nvidia.com>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     Song Liu <songliubraving@fb.com>, Michal Hocko <mhocko@suse.com>,
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        =?ISO-8859-1?Q?J=E9r=F4me?= Glisse <jglisse@redhat.com>,
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        kvm-ppc@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
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Date:   Thu, 03 Oct 2019 18:38:40 -0300
In-Reply-To: <99754d82-33c5-a54f-8607-b6bf151069d4@nvidia.com>
References: <20191003013325.2614-1-leonardo@linux.ibm.com>
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On Thu, 2019-10-03 at 13:49 -0700, John Hubbard wrote:
> Yes. And to clarify, I was assuming that the changes to mm/gup.c were=20
> required in order to accomplish your goals. Given that assumption, I=20
> wanted the generic code to be "proper", and that's what that feedback
> is about.

You assumed right. On my counting approach it's necessary count all
'lockless pagetable walks', including the ones in generic code.

And, I think even without the counting approach, it was a good way
focus this 'lockless pagetable walk' routine in a single place.

>=20
> Although the other questions about file-backed THP
> make it sound like some rethinking across the board is required now.

Yeap, I need to better understand how the file-backed THP problem
works.

Thanks,

Leonardo Br=C3=A1s

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