linux-kernel - Re: [RFC 2/8] shmem: convert to use folio_test

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Message-ID: <CAHbLzkoEAJhz8GG91MSM9+wCYVqseSFzBQdVAP78W5WPq26GHQ@mail.gmail.com>
Date:   Mon, 24 Apr 2023 14:17:12 -0700
From:   Yang Shi <shy828301@...il.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Matthew Wilcox <willy@...radead.org>, hughd@...gle.com,
        akpm@...ux-foundation.org, brauner@...nel.org, djwong@...nel.org,
        p.raghav@...sung.com, da.gomez@...sung.com,
        a.manzanares@...sung.com, dave@...olabs.net, yosryahmed@...gle.com,
        keescook@...omium.org, hare@...e.de, kbusch@...nel.org,
        patches@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC 2/8] shmem: convert to use folio_test_hwpoison()

On Fri, Apr 21, 2023 at 8:05 PM Luis Chamberlain <mcgrof@...nel.org> wrote:
>
> On Fri, Apr 21, 2023 at 11:42:53PM +0100, Matthew Wilcox wrote:
> > On Fri, Apr 21, 2023 at 02:43:54PM -0700, Luis Chamberlain wrote:
> > > The PageHWPoison() call can be converted over to the respective folio call
> > > folio_test_hwpoison(). This introduces no functional changes.
> >
> > Um, no.  Nobody should use folio_test_hwpoison(), it's a nonsense.
> >
> > Individual pages are hwpoisoned.  You're only testing the head page
> > if you use folio_test_hwpoison().  There's folio_has_hwpoisoned() to
> > test if _any_ page in the folio is poisoned.  But blindly converting
> > PageHWPoison to folio_test_hwpoison() is wrong.
>
> Thanks! I don't see folio_has_hwpoisoned() though.

We do have PageHasHWPoisoned(), which indicates at least one subpage
is hwpoisoned in the huge page.

You may need to add a folio variant.

>
>   Luis
>