linux-kernel - Re: [v2 PATCH 3/5] mm: migrate: skip shared exec THP for NUMA balancing

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Date:   Tue, 10 Nov 2020 10:58:29 -0800
From:   Yang Shi <shy828301@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Michal Hocko <mhocko@...e.com>, Zi Yan <ziy@...dia.com>,
        Song Liu <songliubraving@...com>, Mel Gorman <mgorman@...e.de>,
        Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [v2 PATCH 3/5] mm: migrate: skip shared exec THP for NUMA balancing

On Tue, Nov 10, 2020 at 10:16 AM Matthew Wilcox <willy@...radead.org> wrote:
>
> On Tue, Nov 10, 2020 at 10:12:48AM -0800, Yang Shi wrote:
> > @@ -2142,6 +2151,10 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
> >       int page_lru = page_is_file_lru(page);
> >       unsigned long start = address & HPAGE_PMD_MASK;
> >
> > +     if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
> > +         is_shared_exec_page(vma, page))
> > +             goto out;
>
> Why include the IS_ENABLED() check?  Once the ~50 patches I have pending
> go in, shared executable THPs can exist without this option.  And can't
> we have executables on tmpfs today without this option too?

Aha, yes, thanks for reminding. I had the patches baked in my tree
before your patches were posted.

We could have executables on tmpfs w/o that config. Will remove it. Thanks.