Re: [stable] [PATCH] mm: PageBuddy and mapcount underflows robustness

From: Greg KH
Date: Wed Mar 23 2011 - 19:16:31 EST


On Fri, Mar 18, 2011 at 02:34:03PM -0700, Hugh Dickins wrote:
> On Fri, 18 Mar 2011, Andrea Arcangeli wrote:
> > On Mon, Mar 14, 2011 at 10:30:11AM -0700, Linus Torvalds wrote:
> > Subject: mm: PageBuddy and mapcount robustness
> >
> > From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> >
> > Change the _mapcount value indicating PageBuddy from -2 to -128 for
> > more robusteness against page_mapcount() undeflows.
> >
> > Use reset_page_mapcount instead of __ClearPageBuddy in bad_page to
> > ignore the previous retval of PageBuddy().
> >
> > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> > Reported-by: Hugh Dickins <hughd@xxxxxxxxxx>
>
> Yes, this version satisfies my objections too.
> I'd say Acked-by but I see that it's already in, great.
>
> I've Cc'ed stable@xxxxxxxxxx: please can we have this in 2.6.38.1,
> since 2.6.38 regressed the recovery from bad page states,
> inadvertently changing them to a fatal error when CONFIG_DEBUG_VM.

Now queued up for 2.6.38.2, thanks.

greg k-h
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