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

From: Balbir Singh <[email-masked]>
Date: Tue, 11 Apr 2017 18:20:18 +1000

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: [email-masked] # v4.9+
> Signed-off-by: Alexey Kardashevskiy <[email-masked]>
> Acked-by: Balbir Singh <[email-masked]>
> ---
> 
> 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.