Re: [PATCH 2/4] thp: fix regression in handling mlocked pages in __split_huge_pmd()

["Kirill A. Shutemov" <kirill@shutemov.name>]

On Thu, Dec 24, 2015 at 08:17:15PM -0500, Sasha Levin wrote:
> On 12/24/2015 08:12 PM, Dan Williams wrote:
> > On Thu, Dec 24, 2015 at 5:10 PM, Sasha Levin <sasha.levin@oracle.com> wrote:
> >> > On 12/24/2015 06:51 AM, Kirill A. Shutemov wrote:
> >>> >> This patch fixes regression caused by patch
> >>> >>  "mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd"
> >>> >>
> >>> >> The patch makes pmd_trans_huge() check and "page = pmd_page(*pmd)" after
> >>> >> __split_huge_pmd_locked(). It can never succeed, since the pmd already
> >>> >> points to a page table. As result the page is never get munlocked.
> >>> >>
> >>> >> It causes crashes like this:
> >>> >>  http://lkml.kernel.org/r/5661FBB6.6050307@oracle.com
> >> >
> >> > So this patch didn't fix the issue for me. I've sent Kirill the trace
> >> > off-list, but it's essentially the same thing.
> > Can you send me the trace as well, and the reproducer?
> 
> I don't have a simple reproducer, it reproduces rather quickly when running
> under trinity within a KVM guest running a kernel I've attached the config
> for.

Is there a chance to get it reproduced with logs enabled in trinity?
I failed to repoproduce it and code audit isn't fruitful so far.

-- 
 Kirill A. Shutemov

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