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Date:   Fri, 11 Sep 2020 16:40:00 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Vasily Gorbik <gor@linux.ibm.com>
Cc:     John Hubbard <jhubbard@nvidia.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
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        Dave Hansen <dave.hansen@intel.com>,
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        linux-arch <linux-arch@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Russell King <linux@armlinux.org.uk>,
        Mike Rapoport <rppt@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
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        Heiko Carstens <hca@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: Re: [PATCH] mm/gup: fix gup_fast with dynamic page table folding
Message-ID: <20200911194000.GB1221970@ziepe.ca>
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On Fri, Sep 11, 2020 at 09:03:06PM +0200, Vasily Gorbik wrote:
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index e8cbc2e795d5..e899d3506671 100644
> +++ b/include/linux/pgtable.h
> @@ -1427,6 +1427,16 @@ typedef unsigned int pgtbl_mod_mask;
>  #define mm_pmd_folded(mm)	__is_defined(__PAGETABLE_PMD_FOLDED)
>  #endif
>  
> +#ifndef p4d_offset_lockless
> +#define p4d_offset_lockless(pgdp, pgd, address) p4d_offset(&pgd, address)
> +#endif
> +#ifndef pud_offset_lockless
> +#define pud_offset_lockless(p4dp, p4d, address) pud_offset(&p4d, address)
> +#endif
> +#ifndef pmd_offset_lockless
> +#define pmd_offset_lockless(pudp, pud, address) pmd_offset(&pud, address)

Needs brackets: &(pgd) 

These would probably be better as static inlines though, as only s390
compiles will type check pudp like this.

Jason