Re: [PATCH 5.7 233/244] RISC-V: Acquire mmap lock before invoking walk_page_range

[Naresh Kamboju]

RISC-V build breaks on stable-rc 5.7 branch.
build failed with gcc-8, gcc-9 and gcc-9.

On Mon, 20 Jul 2020 at 21:46, Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Atish Patra <atish.patra@xxxxxxx>
>
> commit 0e2c09011d4de4161f615ff860a605a9186cf62a upstream.
>
> As per walk_page_range documentation, mmap lock should be acquired by the
> caller before invoking walk_page_range. mmap_assert_locked gets triggered
> without that. The details can be found here.
>
> http://lists.infradead.org/pipermail/linux-riscv/2020-June/010335.html
>
> Fixes: 395a21ff859c(riscv: add ARCH_HAS_SET_DIRECT_MAP support)
> Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
> Reviewed-by: Michel Lespinasse <walken@xxxxxxxxxx>
> Reviewed-by: Zong Li <zong.li@xxxxxxxxxx>
> Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>
> ---
>  arch/riscv/mm/pageattr.c |   14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -151,6 +151,7 @@ int set_memory_nx(unsigned long addr, in
>
>  int set_direct_map_invalid_noflush(struct page *page)
>  {
> +       int ret;
>         unsigned long start = (unsigned long)page_address(page);
>         unsigned long end = start + PAGE_SIZE;
>         struct pageattr_masks masks = {
> @@ -158,11 +159,16 @@ int set_direct_map_invalid_noflush(struc
>                 .clear_mask = __pgprot(_PAGE_PRESENT)
>         };
>
> -       return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
> +       mmap_read_lock(&init_mm);
> +       ret = walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
> +       mmap_read_unlock(&init_mm);

make -sk KBUILD_BUILD_USER=TuxBuild -C/linux ARCH=riscv
CROSS_COMPILE=riscv64-linux-gnu- HOSTCC=gcc CC="sccache
riscv64-linux-gnu-gcc" O=build defconfig
#
#
make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j32 ARCH=riscv
CROSS_COMPILE=riscv64-linux-gnu- HOSTCC=gcc CC="sccache
riscv64-linux-gnu-gcc" O=build
#
../arch/riscv/mm/pageattr.c: In function âset_direct_map_invalid_noflushâ:
../arch/riscv/mm/pageattr.c:162:2: error: implicit declaration of
function âmmap_read_lockâ; did you mean â_raw_read_lockâ?
[-Werror=implicit-function-declaration]
  162 |  mmap_read_lock(&init_mm);
      |  ^~~~~~~~~~~~~~
      |  _raw_read_lock
../arch/riscv/mm/pageattr.c:164:2: error: implicit declaration of
function âmmap_read_unlockâ; did you mean â_raw_read_unlockâ?
[-Werror=implicit-function-declaration]
  164 |  mmap_read_unlock(&init_mm);
      |  ^~~~~~~~~~~~~~~~
      |  _raw_read_unlock
cc1: some warnings being treated as errors

> +
> +       return ret;
>  }
>
>  int set_direct_map_default_noflush(struct page *page)
>  {
> +       int ret;
>         unsigned long start = (unsigned long)page_address(page);
>         unsigned long end = start + PAGE_SIZE;
>         struct pageattr_masks masks = {
> @@ -170,7 +176,11 @@ int set_direct_map_default_noflush(struc
>                 .clear_mask = __pgprot(0)
>         };
>
> -       return walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
> +       mmap_read_lock(&init_mm);
> +       ret = walk_page_range(&init_mm, start, end, &pageattr_ops, &masks);
> +       mmap_read_unlock(&init_mm);
> +
> +       return ret;
>  }
>
>  void __kernel_map_pages(struct page *page, int numpages, int enable)
>

ref:
full build log with default config.
https://gitlab.com/Linaro/lkft/kernel-runs/-/jobs/647154950

-- 
Linaro LKFT
https://lkft.linaro.org