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Message-ID: <1491898818.8380.3.camel@gmail.com>
Subject: Re: [PATCH kernel v2] powerpc/iommu: Do not call PageTransHuge() on
 tail pages
From: Balbir Singh <bsingharora@gmail.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>, linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>, "Aneesh Kumar K . V"
 <aneesh.kumar@linux.vnet.ibm.com>, Greg Kurz <groug@kaod.org>, Paul
 Mackerras <paulus@samba.org>, linux-kernel@vger.kernel.org,
 stable@vger.kernel.org,  #@ozlabs.ru, v4.9+@ozlabs.ru
Date: Tue, 11 Apr 2017 18:20:18 +1000
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On Tue, 2017-04-11 at 17:54 +1000, 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>
> ---
> 
> Changes:
> v2:
> * instead of moving PageCompound() to the beginning, this just drops
> PageHuge() and PageTransHuge()
>

Looks good! My Acked-by is already present

Balbir Singh.