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From: Andy Lutomirski <luto@amacapital.net>
Date: Thu, 9 Jun 2016 10:24:18 -0700
Message-ID: <CALCETrX1TJ0BBJ40Gu_TNrrdntLdeR42Erg4QMbt5HoN9DqngA@mail.gmail.com>
Subject: Re: [RFC 05/13] x86/mm: Add barriers and document switch_mm-vs-flush synchronization
To: Nadav Amit <nadav.amit@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, Borislav Petkov <bp@alien8.de>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Oleg Nesterov <oleg@redhat.com>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>
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On Fri, Jun 3, 2016 at 10:42 AM, Nadav Amit <nadav.amit@gmail.com> wrote:
> Following this patch, if (current->active_mm != mm), flush_tlb_page() still
> doesn’t call smp_mb() before checking mm_cpumask(mm).
>
> In contrast, flush_tlb_mm_range() does call smp_mb().
>
> Is there a reason for this discrepancy?

Not that I can remember.  Is the remote flush case likely to be racy?

--Andy