From: Andrew Morton <akpm@osdl.org>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: kenneth.w.chen@intel.com, linux-kernel@vger.kernel.org,
linuxppc64-dev@lists.linuxppc.org
Subject: Re: Fix bogus get_page() calls in hugepage code
Date: Thu, 15 Apr 2004 21:49:09 -0700 [thread overview]
Message-ID: <20040415214909.4eeb9ea9.akpm@osdl.org> (raw)
In-Reply-To: <20040416043726.GA26707@zax>
David Gibson <david@gibson.dropbear.id.au> wrote:
>
> On Thu, Apr 15, 2004 at 09:30:11PM -0700, Andrew Morton wrote:
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> > >
> > > On some archs the functions used to implement follow_page() for
> > > hugepages do a get_page(). This is unlike the normal-page path for
> > > follow_page(), so presumably a bug. This patch fixes it.
> >
> > get_user_pages() is supposed to pin the pages which it placed into the
> > callers pages[] array.
> >
> > And the caller of get_user_pages() is supposed to unpin those pages when
> > they are finished with.
> >
> > So follow_hugetlb_page() is currently doing the right thing. The asymmetry
> > with follow_page() is awkward, but the overall intent was to minimise the
> > amount of impact which the hugepage code has on core MM.
>
> Yes, but I'm not talking about follow_hugetlb_page() (my patch doesn't
> touch it). I'm talking about follow_huge_addr() and
> follow_huge_pmd(). These are called to implement follow_page(). In
> get_user_pages(), follow_pages() is bypassed bu the call to
> follow_hugetlb_page(), but these extra get_pages() are presumably a
> bug if follow_page() is called on a hugepage from somewhere other than
> get_user_pages().
Oh, OK. IIRC that stuff was added to support futexes-in-large-pages. The
caller holds ->page_table_lock, as does zap_hugepage_range(), so that seems
fine.
> So I think my patch is correct.
yup, thanks.
prev parent reply other threads:[~2004-04-16 4:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-16 4:12 Fix bogus get_page() calls in hugepage code David Gibson
2004-04-16 4:30 ` Andrew Morton
2004-04-16 4:37 ` David Gibson
2004-04-16 4:49 ` Andrew Morton [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20040415214909.4eeb9ea9.akpm@osdl.org \
--to=akpm@osdl.org \
--cc=david@gibson.dropbear.id.au \
--cc=kenneth.w.chen@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc64-dev@lists.linuxppc.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.