From: Barry Song <v-songbaohua@xxxxxxxx> Platforms like ARM64 have hareware TLB shootdown broadcast. They don't maintain mm_cpumask and they just send tlbi and related sync instructions for TLB flush. So if mm_cpumask is empty, we also allow deferred TLB flush Cc: Nadav Amit <namit@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>> --- mm/rmap.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 5bcb334cd6f2..d320c29a4ad8 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -692,8 +692,13 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) if (!(flags & TTU_BATCH_FLUSH)) return false; - /* If remote CPUs need to be flushed then defer batch the flush */ - if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) + /* + * If remote CPUs need to be flushed then defer batch the flush; + * If ARCHs like ARM64 have hardware TLB flush broadcast, thus + * they don't maintain mm_cpumask() at all, defer batch as well. + */ + if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids || + cpumask_empty(mm_cpumask(mm))) should_defer = true; put_cpu(); -- 2.25.1
