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From: Bibo Mao <maobibo@loongson.cn>
To: Andrew Morton <akpm@linux-foundation.org>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Burton <paulburton@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Daniel Silsby <dansilsby@gmail.com>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: [PATCH 3/3] MIPS: Do not call flush_tlb_all when setting pmd entry
Date: Wed, 24 Jun 2020 17:26:32 +0800
Message-ID: <1592990792-1923-3-git-send-email-maobibo@loongson.cn> (raw)
In-Reply-To: <1592990792-1923-1-git-send-email-maobibo@loongson.cn>

Function set_pmd_at is to set pmd entry, if tlb entry need to
be flushed, there exists pmdp_huge_clear_flush alike function
before set_pmd_at is called. So it is not necessary to call
flush_tlb_all in this function.

In these scenarios, tlb for the pmd range needs to be flushed:
1. privilege degrade such as wrprotect is set on the pmd entry
2. pmd entry is cleared
3. there is exception if set_pmd_at is issued by dup_mmap, since
flush_tlb_mm is called for parent process, it is not necessary
to flush tlb in function copy_huge_pmd.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
 arch/mips/mm/pgtable-32.c | 1 -
 arch/mips/mm/pgtable-64.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/arch/mips/mm/pgtable-32.c b/arch/mips/mm/pgtable-32.c
index bd4b065..61891af 100644
--- a/arch/mips/mm/pgtable-32.c
+++ b/arch/mips/mm/pgtable-32.c
@@ -45,7 +45,6 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 		pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
-	flush_tlb_all();
 }
 #endif /* defined(CONFIG_TRANSPARENT_HUGEPAGE) */
 
diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index 183ff9f..7536f78 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -100,7 +100,6 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 		pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
-	flush_tlb_all();
 }
 
 void __init pagetable_init(void)
-- 
1.8.3.1


  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  9:26 [PATCH 1/3] mm: set page fault address for update_mmu_cache_pmd Bibo Mao
2020-06-24  9:26 ` [PATCH 2/3] mm/huge_memory.c: update tlb entry if pmd is changed Bibo Mao
2020-06-25  0:30   ` Mike Kravetz
2020-06-25  9:57     ` maobibo
2020-06-25 12:01     ` Aneesh Kumar K.V
2020-06-25 16:46       ` Mike Kravetz
2020-06-26  8:13         ` Aneesh Kumar K.V
2020-08-07  4:35           ` Andrew Morton
2020-06-24  9:26 ` Bibo Mao [this message]
2020-06-24 19:49 ` [PATCH 1/3] mm: set page fault address for update_mmu_cache_pmd Andrew Morton
2020-06-30 10:09 ` Kirill A. Shutemov
2020-06-30 10:42   ` maobibo
2020-07-01  2:54     ` maobibo

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