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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Date:   Tue, 14 Nov 2017 08:21:00 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Minchan Kim <minchan@...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 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?
-- 
Michal Hocko
SUSE Labs