linux-kernel - Re: [RFC PATCH] mm: dump_page: print total mapcount for compound page

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Message-ID: <20210531081902.nm3lsw2lp3utrafy@box>
Date:   Mon, 31 May 2021 11:19:02 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Hugh Dickins <hughd@...gle.com>
Cc:     Yang Shi <shy828301@...il.com>, willy@...radead.org,
        jhubbard@...dia.com, kirill.shutemov@...ux.intel.com,
        vbabka@...e.cz, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] mm: dump_page: print total mapcount for compound page

On Fri, May 28, 2021 at 12:47:31PM -0700, Hugh Dickins wrote:
> > page if possible.  But how to implement it safely seems controversial.
> > Some ideas and potential problems have been discussed by
> > https://lore.kernel.org/linux-mm/alpine.LSU.2.11.2105261733110.16920@eggly.anvils/.
> > 
> > So I prepared this patch to show a possible approach to get some
> > feedback.  The same thing could be decoded by the reader of page dump
> > as well by using the same formula used by this patch.  However it sounds
> > more convenient to have kernel do the math.
> >  
> >  mm/debug.c | 35 +++++++++++++++++++++++++++++------
> >  1 file changed, 29 insertions(+), 6 deletions(-)
> 
> Adding that code to come up with a deceptive approximation to a number
> which most sites won't care about: speaking for me, I'll say no.

I agree. The approximation may bring more confusion than help debugging.

-- 
 Kirill A. Shutemov