> The cpumask_empty() is indeed just another memory access, which is most > likely ok. But wouldn’t adding something like CONFIG_ARCH_HAS_MM_CPUMASK > make the code simpler and (slightly, certainly slightly) more performant? Yep. good suggestion, Nadav. So the code will be as below, right? diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index be0b95e51df6..a91d73866238 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -81,6 +81,7 @@ config X86 select ARCH_HAS_KCOV if X86_64 select ARCH_HAS_MEM_ENCRYPT select ARCH_HAS_MEMBARRIER_SYNC_CORE + select ARCH_HAS_MM_CPUMASK select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE select ARCH_HAS_PMEM_API if X86_64 select ARCH_HAS_PTE_DEVMAP if X86_64 diff --git a/mm/Kconfig b/mm/Kconfig index 169e64192e48..7bf54f57ca01 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -951,6 +951,9 @@ config ARCH_HAS_CURRENT_STACK_POINTER register alias named "current_stack_pointer", this config can be selected. +config ARCH_HAS_MM_CPUMASK + bool + config ARCH_HAS_VM_GET_PAGE_PROT bool diff --git a/mm/rmap.c b/mm/rmap.c index 5bcb334cd6f2..13d4f9a1d4f1 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -692,6 +692,10 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) if (!(flags & TTU_BATCH_FLUSH)) return false; +#ifndef CONFIG_ARCH_HAS_MM_CPUMASK + return true; +#endif + /* If remote CPUs need to be flushed then defer batch the flush */ if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) should_defer = true; Thanks Barry
