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Date: Tue, 12 Dec 2017 09:32:09 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Jinpu Wang <jinpu.wang@profitbricks.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Hillf Danton <hillf.zj@alibaba-inc.com>,
        stable <stable@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 1/3] thp: reduce indentation level in change_huge_pmd()
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On Thu, Dec 07, 2017 at 01:25:19PM +0100, Jinpu Wang wrote:
> On Thu, Dec 7, 2017 at 1:05 PM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Thu, Dec 07, 2017 at 11:22:50AM +0100, Jack Wang wrote:
> >> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> >>
> >> commit 0a85e51d37645e9ce57e5e1a30859e07810ed07c upstream.
> >>
> >> Patch series "thp: fix few MADV_DONTNEED races"
> >>
> >> For MADV_DONTNEED to work properly with huge pages, it's critical to not
> >> clear pmd intermittently unless you hold down_write(mmap_sem).
> >>
> >> Otherwise MADV_DONTNEED can miss the THP which can lead to userspace
> >> breakage.
> >>
> >> See example of such race in commit message of patch 2/4.
> >>
> >> All these races are found by code inspection.  I haven't seen them
> >> triggered.  I don't think it's worth to apply them to stable@.
> >>
> >> This patch (of 4):
> >
> > What about all 4 of these?
> The 4 patches were from here:
> http://lkml.iu.edu/hypermail/linux/kernel/1703.0/01274.html
> 
> thp: reduce indentation level in change_huge_pmd()
> thp: fix MADV_DONTNEED vs. numa balancing race
> thp: fix MADV_DONTNEED vs. MADV_FREE race (the function exists only since 4.5+ )
> thp: fix MADV_DONTNEED vs clear soft dirty race (this one already
> included since 4.4.63)
> 
> >
> > And should this also go into 4.9?  I don't want to include fixes into
> > 4.4-stable without them also being in 4.9-stable, as that would be a
> > regression for people upgrading.
> In 4.9, the last 2 were already applied, I will try to backport these
> 3 commits also to 4.9 stable.

Thanks for all of these now, all queued up.

greg k-h