linux-kernel - Re: [PATCH v1 1/4] mm: introduce MADV

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Date:   Thu, 20 Jun 2019 11:57:09 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Tim Murray <timmurray@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Daniel Colascione <dancol@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Sonny Rao <sonnyrao@...gle.com>,
        Brian Geffon <bgeffon@...gle.com>,
        Jann Horn <jannh@...gle.com>, Oleg Nesterov <oleg@...hat.com>,
        Christian Brauner <christian@...uner.io>, oleksandr@...hat.com,
        hdanton@...a.com, Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: [PATCH v1 1/4] mm: introduce MADV_COLD

On Thu, Jun 20, 2019 at 1:01 AM Minchan Kim <minchan@...nel.org> wrote:
[snip]
> > > >
> > > > I think to fix this, what you should do is clear the PG_Idle flag if the
> > > > young/accessed PTE bits are set. If PG_Idle is already cleared, then you
> > > > don't need to do anything.
> > >
> > > I'm not sure. What does it make MADV_COLD special?
> > > How about MADV_FREE|MADV_DONTNEED?
> > > Why don't they clear PG_Idle if pte was young at tearing down pte?
> >
> > Good point, so it sounds like those (MADV_FREE|MADV_DONTNEED) also need to be fixed then?
>
> Not sure. If you want it, maybe you need to fix every pte clearing and pte_mkold
> part, which is more general to cover every sites like munmap, get_user_pages and
> so on. Anyway, I don't think it's related to this patchset.

Ok, I can look into this issue on my own when I get time. I'll add it
to my list. No problems with your patch otherwise from my side.

 -Joel