Re: [kernel,v2] powerpc/iommu: Do not call PageTransHuge() on tail pages

From	Michael Ellerman <patch-notifications@ellerman.id.au>
Newsgroups	linux.kernel
Subject	Re: [kernel,v2] powerpc/iommu: Do not call PageTransHuge() on tail pages
Date	2017-04-20 00:10 +0200
Message-ID	<ty5Xr-ug-1@gated-at.bofh.it> (permalink)
References	<tuZ2a-4oA-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, 2017-04-11 at 07:54:57 UTC, Alexey Kardashevskiy wrote:
> The CMA pages migration code does not support compound pages at
> the moment so it performs few tests before proceeding to actual page
> migration.
> 
> One of the tests - PageTransHuge() - has VM_BUG_ON_PAGE(PageTail()) as
> it is designed to be called on head pages only. Since we also test for
> PageCompound(), and it contains PageTail() and PageHead(), we can
> simplify the check by leaving just PageCompound() and therefore avoid
> possible VM_BUG_ON_PAGE.
> 
> Fixes: 2e5bbb5461f1 ("KVM: PPC: Book3S HV: Migrate pinned pages out of CMA")
> Cc: stable@vger.kernel.org # v4.9+
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> Acked-by: Balbir Singh <bsingharora@gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/e889e96e98e8da97bd39e46b725361

cheers

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[PATCH kernel v2] powerpc/iommu: Do not call PageTransHuge() on tail pages Alexey Kardashevskiy <aik@ozlabs.ru> - 2017-04-11 10:10 +0200
  Re: [PATCH kernel v2] powerpc/iommu: Do not call PageTransHuge() on  tail pages Balbir Singh <bsingharora@gmail.com> - 2017-04-11 10:30 +0200
  Re: [kernel,v2] powerpc/iommu: Do not call PageTransHuge() on tail pages Michael Ellerman <patch-notifications@ellerman.id.au> - 2017-04-20 00:10 +0200

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