Re: [PATCH V5 0/3] riscv: mm: Add soft-dirty and uffd-wp support

[Alexandre Ghiti]

Hi Chunyan,

On 13/11/2024 10:58, Chunyan Zhang wrote:
> This patchset adds soft dirty and userfaultfd write protect tracking
> support for RISC-V.
>
> As described in the patches, we are trying to utilize only one free PTE
> bit(9) to support three kernel features (devmap, soft-dirty, uffd-wp).
> Users cannot have them supported at the same time (have to select
> one when building the kernel).
>
> This patchset has been tested with:
> 1) The kselftest mm suite in which soft-dirty, madv_populate,
> test_unmerge_uffd_wp, and uffd-unit-tests run and pass, and no regressions
> are observed in any of the other tests.
>
> 2) CRIU:
> - 'criu check --feature mem_dirty_track' returns supported;
> - incremental_dumps[1] and simple_loop [2] dump and restores work fine;
> - zdtm test suite can run under host mode.
>
> This patchset applies on top of v6.12-rc7.
>
> V5:
> - Fixed typos and corrected some words in Kconfig and commit message;
> - Removed pte_wrprotect() from pte_swp_mkuffd_wp(), this is a copy-paste error;
> - Added Alex's Reviewed-by tag in patch 2.
>
> V4:
> - Added bit(4) descriptions into "Format of swap PTE".
>
> V3:
> - Fixed the issue reported by kernel test irobot <lkp@xxxxxxxxx>.
>
> V1 -> V2:
> - Add uffd-wp supported;
> - Make soft-dirty uffd-wp and devmap mutually exclusive which all use the same PTE bit;
> - Add test results of CRIU in the cover-letter.
>
> [1] https://www.criu.org/Incremental_dumps
> [2] https://asciinema.org/a/232445
>
> Chunyan Zhang (3):
>    riscv: mm: Prepare for reusing PTE RSW bit(9)
>    riscv: mm: Add soft-dirty page tracking support
>    riscv: mm: Add uffd write-protect support
>
>   arch/riscv/Kconfig                    |  34 ++++++-
>   arch/riscv/include/asm/pgtable-64.h   |   2 +-
>   arch/riscv/include/asm/pgtable-bits.h |  31 ++++++
>   arch/riscv/include/asm/pgtable.h      | 133 +++++++++++++++++++++++++-
>   4 files changed, 197 insertions(+), 3 deletions(-)


As mentioned by Deepak, there is a new proposed extension Svrsw60t59b 
which will free 2 more bits. It would help if you can come up with a new 
version of this patchset using this new extension, would you mind 
working on this? If not possible, let's discuss how I can help.

Thanks,

Alex