[PATCH v10 3/4] mm/tlbbatch: Introduce arch_flush_tlb_batched_pending()

Yicong Yang
2023-07-10T08:43:24Z

From: Yicong Yang <yangyicong@hisilicon.com>

Currently we'll flush the mm in flush_tlb_batched_pending() to
avoid race between reclaim unmaps pages by batched TLB flush
and mprotect/munmap/etc. Other architectures like arm64 may
only need a synchronization barrier(dsb) here rather than
a full mm flush. So add arch_flush_tlb_batched_pending() to
allow an arch-specific implementation here. This intends no
functional changes on x86 since still a full mm flush for
x86.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
arch/x86/include/asm/tlbflush.h | 5 +++++
mm/rmap.c | 2 +-
2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 1c7d3a36e16c..837e4a50281a 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -284,6 +284,11 @@ static inline void arch_tlbbatch_add_pending(struct arch_tlbflush_unmap_batch *b
cpumask_or(&batch->cpumask, &batch->cpumask, mm_cpumask(mm));
}

+static inline void arch_flush_tlb_batched_pending(struct mm_struct *mm)
+{
+ flush_tlb_mm(mm);
+}
+
extern void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch);

static inline bool pte_flags_need_flush(unsigned long oldflags,
diff --git a/mm/rmap.c b/mm/rmap.c
index 9699c6011b0e..3a16c91be7e2 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -717,7 +717,7 @@ void flush_tlb_batched_pending(struct mm_struct *mm)
int flushed = batch >> TLB_FLUSH_BATCH_FLUSHED_SHIFT;

if (pending != flushed) {
- flush_tlb_mm(mm);
+ arch_flush_tlb_batched_pending(mm);
/*
* If the new TLB flushing is pending during flushing, leave
* mm->tlb_flush_batched as is, to avoid losing flushing.
--
2.24.0