linux-kernel - [PATCH v10 3/4] mm/tlbbatch: Introduce arch_flush_tlb_batched

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Date:   Mon, 10 Jul 2023 16:39:13 +0800
From:   Yicong Yang <yangyicong@...wei.com>
To:     <akpm@...ux-foundation.org>, <catalin.marinas@....com>,
        <linux-mm@...ck.org>, <linux-arm-kernel@...ts.infradead.org>,
        <x86@...nel.org>, <mark.rutland@....com>, <ryan.roberts@....com>,
        <will@...nel.org>, <anshuman.khandual@....com>,
        <linux-doc@...r.kernel.org>
CC:     <corbet@....net>, <peterz@...radead.org>, <arnd@...db.de>,
        <punit.agrawal@...edance.com>, <linux-kernel@...r.kernel.org>,
        <darren@...amperecomputing.com>, <yangyicong@...ilicon.com>,
        <huzhanyuan@...o.com>, <lipeifeng@...o.com>,
        <zhangshiming@...o.com>, <guojian@...o.com>, <realmz6@...il.com>,
        <linux-mips@...r.kernel.org>, <openrisc@...ts.librecores.org>,
        <linuxppc-dev@...ts.ozlabs.org>, <linux-riscv@...ts.infradead.org>,
        <linux-s390@...r.kernel.org>, Barry Song <21cnbao@...il.com>,
        <wangkefeng.wang@...wei.com>, <xhao@...ux.alibaba.com>,
        <prime.zeng@...ilicon.com>, <Jonathan.Cameron@...wei.com>
Subject: [PATCH v10 3/4] mm/tlbbatch: Introduce arch_flush_tlb_batched_pending()

From: Yicong Yang <yangyicong@...ilicon.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@...ilicon.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