linux-kernel - Re: [PATCH v4] mm: Add PM_HUGE_THP

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Message-ID: <YY4bFPkfUhlpUqvo@xz-m1.local>
Date:   Fri, 12 Nov 2021 15:43:16 +0800
From:   Peter Xu <peterx@...hat.com>
To:     Mina Almasry <almasrymina@...gle.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Paul E . McKenney" <paulmckrcu@...com>,
        Yu Zhao <yuzhao@...gle.com>, Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ivan Teterevkov <ivan.teterevkov@...anix.com>,
        Florian Schmidt <florian.schmidt@...anix.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v4] mm: Add PM_HUGE_THP_MAPPING to /proc/pid/pagemap

On Wed, Nov 10, 2021 at 09:50:13AM -0800, Mina Almasry wrote:
> On Tue, Nov 9, 2021 at 11:03 PM Peter Xu <peterx@...hat.com> wrote:
> >
> > The ending "_MAPPING" seems redundant to me, how about just call it "PM_THP" or
> > "PM_HUGE" (as THP also means HUGE already)?
> >
> 
> So I want to make it clear that the flag is set only when the page is
> PMD mappend and is a THP (not hugetlbfs or some other PMD device
> mapping). PM_THP would imply the flag is set only if the underlying
> page is THP without regard to whether it's actually PMD mapped or not.

I see, that's fine.

However as I mentioned I still think HUGE and THP dup with each other.
Meanwhile, "MAPPING" does not sound like a boolean status on whether it's thp
mapped..

If you still prefer this approach, how about PM_THP_MAPPED?

-- 
Peter Xu