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Date: Wed, 15 Nov 2017 09:12:36 +0900
From: Minchan Kim <minchan@kernel.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, will.deacon@arm.com,
        Bob Liu <liubo95@huawei.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Roman Gushchin <guro@fb.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] arch, mm: introduce arch_tlb_gather_mmu_lazy (was: Re:
 [RESEND PATCH] mm, oom_reaper: gather each vma to prevent) leaking TLB entry
Message-ID: <20171115001236.GA23810@bbox>
References: <20171107095453.179940-1-wangnan0@huawei.com>
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 <20171113002833.GA18301@bbox>
 <20171113095107.24hstywywxk7nx7e@dhcp22.suse.cz>
 <20171114014549.GA1995@bgram>
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On Tue, Nov 14, 2017 at 08:21:00AM +0100, Michal Hocko wrote:
> On Tue 14-11-17 10:45:49, Minchan Kim wrote:
> [...]
> > Anyway, I think Wang Nan's patch is already broken.
> > http://lkml.kernel.org/r/%3C20171107095453.179940-1-wangnan0@huawei.com%3E
> > 
> > Because unmap_page_range(ie, zap_pte_range) can flush TLB forcefully
> > and free pages. However, the architecture code for TLB flush cannot
> > flush at all by wrong fullmm so other threads can write freed-page.
> 
> I am not sure I understand what you mean. How is that any different from
> any other explicit partial madvise call?

Argh, I misread his code. Sorry for that.