linux-kernel - 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

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Message-ID: <20171115001236.GA23810@bbox>
Date:   Wed, 15 Nov 2017 09:12:36 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Wang Nan <wangnan0@...wei.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, will.deacon@....com,
        Bob Liu <liubo95@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Ingo Molnar <mingo@...nel.org>, Roman Gushchin <guro@...com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Andrea Arcangeli <aarcange@...hat.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

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.