Re: [PATCH v2 2/2] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs
From: Peter Zijlstra <peterz@infradead.org>
Date: 2023-07-03 13:58:26
Also in:
linux-arch, linux-arm-kernel, linux-mm, linux-s390, lkml, sparclinux
On Tue, Jun 20, 2023 at 05:46:18PM +0300, Yair Podemsky wrote:
quoted hunk ↗ jump to hunk
@@ -191,7 +191,13 @@ static void tlb_remove_table_smp_sync(void *arg) /* Simply deliver the interrupt */ } -void tlb_remove_table_sync_one(void) +#ifdef CONFIG_ARCH_HAS_CPUMASK_BITS +#define REMOVE_TABLE_IPI_MASK mm_cpumask(mm) +#else +#define REMOVE_TABLE_IPI_MASK cpu_online_mask +#endif /* CONFIG_ARCH_HAS_CPUMASK_BITS */ + +void tlb_remove_table_sync_one(struct mm_struct *mm) { /* * This isn't an RCU grace period and hence the page-tables cannot be@@ -200,7 +206,8 @@ void tlb_remove_table_sync_one(void) * It is however sufficient for software page-table walkers that rely on * IRQ disabling. */ - smp_call_function(tlb_remove_table_smp_sync, NULL, 1); + on_each_cpu_mask(REMOVE_TABLE_IPI_MASK, tlb_remove_table_smp_sync, + NULL, true);
Aside from what Dave said about the REMOVE_TABLE_IPI_MASK thing, this isn't right. on_each_cpu_mask() includes the current cpu, while smp_call_function() explicitly does not. Yes, they all end up in smp_call_function_many_cond(), but the on_each_cpu*() family will have SCF_RUN_LOCAL set, while the smp_call_function*() family will not.