Re: [PATCH 0/2] kernel BUG at mm/huge_memory.c:212!

From: Kirill A. Shutemov
Date: Wed Dec 12 2012 - 05:57:42 EST


On Wed, Dec 12, 2012 at 01:36:36PM +0800, Bob Liu wrote:
> On Mon, Dec 3, 2012 at 9:02 PM, Jiri Slaby <jslaby@xxxxxxx> wrote:
> > On 11/30/2012 04:03 PM, Kirill A. Shutemov wrote:
> >> From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> >>
> >> Hi Jiri,
> >>
> >> Sorry for late answer. It took time to reproduce and debug the issue.
> >>
> >> Could you test two patches below by thread. I expect it to fix both
> >> issues: put_huge_zero_page() and Bad rss-counter state.
> >
> > Hi, yes, since applying the patches on the last Thu, it didn't recur.
> >
> >> Kirill A. Shutemov (2):
> >> thp: fix anononymous page accounting in fallback path for COW of HZP
> >> thp: avoid race on multiple parallel page faults to the same page
> >>
> >> mm/huge_memory.c | 30 +++++++++++++++++++++++++-----
> >> 1 file changed, 25 insertions(+), 5 deletions(-)
> >
>
> I still saw this bug on 3.7.0-rc8, but it's hard to reproduce it.
> It appears only once.

I guess the patch you've posted fixes the issue, right?

It's useful to enable debug_cow to test fallback path:

echo 1 > /sys/kernel/mm/transparent_hugepage/debug_cow

--
Kirill A. Shutemov

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