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    SubjectRe: [RFC PATCH 2/2] mm: mmu_notifier fix for tlb_end_vma (build failures)
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    On Fri, 24 Aug 2018 06:50:48 PDT (-0700), Will Deacon wrote:
    > On Fri, Aug 24, 2018 at 02:34:27PM +0100, Will Deacon wrote:
    >> On Fri, Aug 24, 2018 at 06:24:19AM -0700, Guenter Roeck wrote:
    >> > On Fri, Aug 24, 2018 at 02:10:27PM +0100, Will Deacon wrote:
    >> > > On Fri, Aug 24, 2018 at 06:07:22AM -0700, Guenter Roeck wrote:
    >> > > > On Thu, Aug 23, 2018 at 06:47:09PM +1000, Nicholas Piggin wrote:
    >> > > > > The generic tlb_end_vma does not call invalidate_range mmu notifier,
    >> > > > > and it resets resets the mmu_gather range, which means the notifier
    >> > > > > won't be called on part of the range in case of an unmap that spans
    >> > > > > multiple vmas.
    >> > > > >
    >> > > > > ARM64 seems to be the only arch I could see that has notifiers and
    >> > > > > uses the generic tlb_end_vma. I have not actually tested it.
    >> > > > >
    >> > > > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
    >> > > > > Acked-by: Will Deacon <will.deacon@arm.com>
    >> > > >
    >> > > > This patch breaks riscv builds in mainline.
    >> > >
    >> > > Looks very similar to the breakage we hit on arm64. diff below should fix
    >> > > it.
    >> > >
    >> >
    >> > Unfortunately it doesn't.
    >> >
    >> > In file included from ./arch/riscv/include/asm/pgtable.h:26:0,
    >> > from ./include/linux/memremap.h:7,
    >> > from ./include/linux/mm.h:27,
    >> > from arch/riscv/mm/fault.c:23:
    >> > ./arch/riscv/include/asm/tlb.h: In function ‘tlb_flush’:
    >> > ./arch/riscv/include/asm/tlb.h:19:18: error: dereferencing pointer to incomplete type ‘struct mmu_gather’
    >> > flush_tlb_mm(tlb->mm);
    >> > ^
    >>
    >> Sorry, I was a bit quick of the mark there. You'll need a forward
    >> declaration for the paramater type. Here it is with a commit message,
    >> although still untested because I haven't got round to setting up a riscv
    >> toolchain yet.

    FWIW, Arnd built them last time he updated the cross tools so you should be
    able to get GCC 8.1.0 for RISC-V from there. I use this make.cross script that
    I stole from the Intel 0-day robot

    https://github.com/palmer-dabbelt/home/blob/master/.local/src/local-scripts/make.cross.bash

    If I'm reading it correctly the tools come from here

    http://cdn.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/x86_64-gcc-8.1.0-nolibc-riscv64-linux.tar.gz

    I use the make.cross script as it makes it super easy to test my
    across-the-tree patches on other people's ports.

    >>
    >> Will
    >>
    >> --->8
    >>
    >> From adb9be33d68320edcda80d540a97a647792894d2 Mon Sep 17 00:00:00 2001
    >> From: Will Deacon <will.deacon@arm.com>
    >> Date: Fri, 24 Aug 2018 14:33:48 +0100
    >> Subject: [PATCH] riscv: tlb: Provide definition of tlb_flush() before
    >> including tlb.h
    >>
    >> As of commit fd1102f0aade ("mm: mmu_notifier fix for tlb_end_vma"),
    >> asm-generic/tlb.h now calls tlb_flush() from a static inline function,
    >> so we need to make sure that it's declared before #including the
    >> asm-generic header in the arch header.
    >>
    >> Since tlb_flush() is a one-liner for riscv, we can define it before
    >> including asm-generic/tlb.h as long as we provide a forward declaration
    >> of struct mmu_gather.
    >>
    >> Reported-by: Guenter Roeck <linux@roeck-us.net>
    >> Signed-off-by: Will Deacon <will.deacon@arm.com>
    >> ---
    >> arch/riscv/include/asm/tlb.h | 4 +++-
    >> 1 file changed, 3 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/arch/riscv/include/asm/tlb.h b/arch/riscv/include/asm/tlb.h
    >> index c229509288ea..a3d1380ad970 100644
    >> --- a/arch/riscv/include/asm/tlb.h
    >> +++ b/arch/riscv/include/asm/tlb.h
    >> @@ -14,11 +14,13 @@
    >> #ifndef _ASM_RISCV_TLB_H
    >> #define _ASM_RISCV_TLB_H
    >>
    >> -#include <asm-generic/tlb.h>
    >> +struct mmu_gather;
    >>
    >> static inline void tlb_flush(struct mmu_gather *tlb)
    >> {
    >> flush_tlb_mm(tlb->mm);
    >
    > Bah, didn't spot the dereference so this won't work either. You basically
    > just need to copy what I did for arm64 in d475fac95779.
    >
    > Will

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