Re: [PATCH] riscv: Use an atomic xchg in pudp_huge_get_and_clear()

Hi Alex,

On Thu, 14 Aug 2025, Alexandre Ghiti wrote:

Make sure we return the right pud value and not a value that could have been overwritten in between by a different core.

Fixes: c3cc2a4a3a23 ("riscv: Add support for PUD THP") Cc: stable@vger.kernel.org Signed-off-by: Alexandre Ghiti alexghiti@rivosinc.com

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Note that this will conflict with https://lore.kernel.org/linux-riscv/20250625063753.77511-1-ajd@linux.ibm.com... if applied after 6.17.

Two quick questions on this one:

- I see that you're using atomic_long_xchg() here and in some similar functions in pgtable.h, rather than xchg(). Was curious about the rationale for that?

- x86 avoids the xchg() for !CONFIG_SMP. Should we do the same?

thanks,

- Paul