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Date:   Wed, 06 Dec 2023 05:14:26 -0800 (PST)
Subject:     Re: [PATCH 0/2] riscv: Increase mmap_rnd_bits_max on Sv48/57
In-Reply-To: <20230929211155.3910949-4-samitolvanen@google.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>, aou@eecs.berkeley.edu,
        akpm@linux-foundation.org, keescook@chromium.org,
        linux-mm@kvack.org, linux-riscv@lists.infradead.org,
        llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
        samitolvanen@google.com
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     samitolvanen@google.com
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On Fri, 29 Sep 2023 14:11:56 PDT (-0700), samitolvanen@google.com wrote:
> Hi all,
>
> We noticed that 64-bit RISC-V kernels limit mmap_rnd_bits to 24
> even if the hardware supports a larger virtual address space size
> [1]. These two patches allow mmap_rnd_bits_max to be changed during
> init, and bumps up the maximum randomness if we end up setting up
> 4/5-level paging at boot.

Sorry for missing this, I'm just poking through old stuff in patchwork.  
As far as I can tell this is still relevant, the discussions are just on 
the mmap() bits (but we'd already screwed that one up and have since 
fixed it).

So

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>

in case someone else wants to take it, but I'm OK taking that MM patch 
with Kees' review.

>
> Sami
>
>  [1] https://github.com/google/android-riscv64/issues/1
>
>
> Sami Tolvanen (2):
>   mm: Change mmap_rnd_bits_max to __ro_after_init
>   riscv: mm: Update mmap_rnd_bits_max
>
>  arch/riscv/mm/init.c | 6 ++++++
>  include/linux/mm.h   | 2 +-
>  mm/mmap.c            | 2 +-
>  3 files changed, 8 insertions(+), 2 deletions(-)
>
>
> base-commit: 6465e260f48790807eef06b583b38ca9789b6072