linux-kernel - Re: [v2 PATCH] mm: thp: fix false negative of shmem vma's THP eligibility

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Message-ID: <20190607142525.GH18435@dhcp22.suse.cz>
Date:   Fri, 7 Jun 2019 16:25:25 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     Yang Shi <yang.shi@...ux.alibaba.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        vbabka@...e.cz, rientjes@...gle.com, kirill@...temov.name,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [v2 PATCH] mm: thp: fix false negative of shmem vma's THP
 eligibility

On Fri 07-06-19 03:57:18, Hugh Dickins wrote:
[...]
> The addition of "THPeligible" without an "Anon" in its name was
> unfortunate. I suppose we're two releases too late to change that.

Well, I do not really see any reason why THPeligible should be Anon
specific at all. Even if ...

> Applying process (PR_SET_THP_DISABLE) and mm (MADV_*HUGEPAGE)
> limitations to shared filesystem objects doesn't work all that well.

... this is what we are going with then it is really important to have a
single place to query the eligibility IMHO.

> I recommend that you continue to treat shmem objects separately from
> anon memory, and just make the smaps "THPeligible" more often accurate.

Agreed on this.

-- 
Michal Hocko
SUSE Labs