linux-kernel - Re: [PATCH] selftest/mm: Do not use hint for riscv mmap

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Message-ID: <ZuNTWCsPPLTm1zdX@ghost>
Date: Thu, 12 Sep 2024 13:47:20 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Chunyan Zhang <zhangchunyan@...as.ac.cn>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Shuah Khan <shuah@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Alexandre Ghiti <alex@...ti.fr>, linux-mm@...ck.org,
	linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org, Chunyan Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH] selftest/mm: Do not use hint for riscv mmap

On Thu, Sep 12, 2024 at 06:00:18PM +0800, Chunyan Zhang wrote:
> When the virtual address range selftest is run on RISC-V platforms,
> it is observed that using the hint address when calling mmap cannot
> get the address in the range of that validate_addr() checks, also
> that will cause '/proc/self/maps' have gaps larger than MAP_CHUNK_SIZE.
> 
> Signed-off-by: Chunyan Zhang <zhangchunyan@...as.ac.cn>
> ---
>  tools/testing/selftests/mm/virtual_address_range.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
> index 4e4c1e311247..25f3eb304999 100644
> --- a/tools/testing/selftests/mm/virtual_address_range.c
> +++ b/tools/testing/selftests/mm/virtual_address_range.c
> @@ -64,6 +64,14 @@
>  #define NR_CHUNKS_HIGH  NR_CHUNKS_384TB
>  #endif
>  
> +#if defined(__riscv) && (__riscv_xlen == 64)
> +static char *hind_addr(void)

This is not a typo by you since this is the name of the original
function but this should be "hint_addr" right?

> +{
> +	return NULL;
> +}
> +
> +static void validate_addr(char *ptr, int high_addr) { }
> +#else

This is something that I am trying to solve over at
https://lore.kernel.org/lkml/20240905-patches-below_hint_mmap-v3-0-3cd5564efbbb@rivosinc.com/
(the solution is still in flux). Since riscv doesn't currently have this
behavior of restricting the virtual address space, I think it is more
reasonable to disable this test entirely. After we have a longer-term
solution with the patch I have up we can adjust the test and re-enable
it. What do you think?

- Charlie

>  static char *hind_addr(void)
>  {
>  	int bits = HIGH_ADDR_SHIFT + rand() % (63 - HIGH_ADDR_SHIFT);
> @@ -81,6 +89,7 @@ static void validate_addr(char *ptr, int high_addr)
>  	if (addr > HIGH_ADDR_MARK)
>  		ksft_exit_fail_msg("Bad address %lx\n", addr);
>  }
> +#endif
>  
>  static int validate_lower_address_hint(void)
>  {
> -- 
> 2.34.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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