The lockless GUP fast path needs the architecture to distinguish PTEs with no struct page behind them and to keep page table pages alive while a walker holds no lock. Alpha now has ARCH_HAS_PTE_SPECIAL, and it has selected MMU_GATHER_RCU_TABLE_FREE for a long time, so both requirements are met.
PTEs are a single 64-bit word on Alpha, so the lockless reads that the generic walker performs cannot tear, and no arch-specific gup_fast_permitted() or ptep_get_lockless() is needed. Assisted-by: Claude:claude-opus-5 Signed-off-by: Matt Turner <[email protected]> Tested-by: Magnus Lindholm <[email protected]> Reviewed-by: Magnus Lindholm <[email protected]> --- arch/alpha/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 4bd5e913baaf..1ba262812212 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -28,6 +28,7 @@ config ALPHA select HAVE_ARCH_COMPILER_H select HAVE_ASM_MODVERSIONS select HAVE_DEBUG_KMEMLEAK + select HAVE_GUP_FAST select HAVE_PAGE_SIZE_8KB select HAVE_PCSPKR_PLATFORM select HAVE_PERF_EVENTS -- 2.54.0
