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Subject: Re: [PATCH 01/26] mm: Do page fault accounting in handle_mm_fault
To:     Peter Xu <peterx@redhat.com>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
CC:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Gerald Schaefer <gerald.schaefer@de.ibm.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Will Deacon <will@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>
References: <20200626223130.199227-1-peterx@redhat.com>
 <20200626223130.199227-2-peterx@redhat.com>
From:   John Hubbard <jhubbard@nvidia.com>
Message-ID: <370e06f7-a93b-21c9-c58e-57ad6ed8f8a8@nvidia.com>
Date:   Sun, 28 Jun 2020 18:52:24 -0700
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On 2020-06-26 15:31, Peter Xu wrote:
> This is a preparation patch to move page fault accountings into the general
> code in handle_mm_fault().  This includes both the per task flt_maj/flt_min
> counters, and the major/minor page fault perf events.  To do this, the pt_regs
> pointer is passed into handle_mm_fault().
> 
> PERF_COUNT_SW_PAGE_FAULTS should still be kept in per-arch page fault handlers.
> 
> So far, all the pt_regs pointer that passed into handle_mm_fault() is NULL,
> which means this patch should have no intented functional change.
> 
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>   arch/alpha/mm/fault.c         |  2 +-
>   arch/arc/mm/fault.c           |  2 +-
>   arch/arm/mm/fault.c           |  2 +-
>   arch/arm64/mm/fault.c         |  2 +-
>   arch/csky/mm/fault.c          |  3 +-
>   arch/hexagon/mm/vm_fault.c    |  2 +-
>   arch/ia64/mm/fault.c          |  2 +-
>   arch/m68k/mm/fault.c          |  2 +-
>   arch/microblaze/mm/fault.c    |  2 +-
>   arch/mips/mm/fault.c          |  2 +-
>   arch/nds32/mm/fault.c         |  2 +-
>   arch/nios2/mm/fault.c         |  2 +-
>   arch/openrisc/mm/fault.c      |  2 +-
>   arch/parisc/mm/fault.c        |  2 +-
>   arch/powerpc/mm/copro_fault.c |  2 +-
>   arch/powerpc/mm/fault.c       |  2 +-
>   arch/riscv/mm/fault.c         |  2 +-
>   arch/s390/mm/fault.c          |  2 +-
>   arch/sh/mm/fault.c            |  2 +-
>   arch/sparc/mm/fault_32.c      |  4 +--
>   arch/sparc/mm/fault_64.c      |  2 +-
>   arch/um/kernel/trap.c         |  2 +-
>   arch/unicore32/mm/fault.c     |  2 +-
>   arch/x86/mm/fault.c           |  2 +-
>   arch/xtensa/mm/fault.c        |  2 +-
>   drivers/iommu/amd_iommu_v2.c  |  2 +-

The above file is renamed, as of a couple weeks ago, via
commit ad8694bac410 ("iommu/amd: Move AMD IOMMU driver into
subdirectory").

Also there are a number of changes to mm/gup.c (not a concern for this
patch, but it is for the overall series). So I'm hoping you're going to
post a version that is rebased against 5.8-rc*.

thanks,
-- 
John Hubbard
NVIDIA