[112/173] MIPS: do not call flush_tlb_all when setting pmd entry

Commit Message

Andrew Morton Feb. 24, 2021, 8:06 p.m. UTC

From: Bibo Mao <[e-mail]>
Subject: MIPS: do not call flush_tlb_all when setting pmd entry

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.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Bibo Mao <[e-mail]>
Cc: Anshuman Khandual <[e-mail]>
Cc: Daniel Silsby <[e-mail]>
Cc: "Kirill A. Shutemov" <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Paul Burton <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: Thomas Bogendoerfer <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 arch/mips/mm/pgtable-32.c |    1 -
 arch/mips/mm/pgtable-64.c |    1 -
 2 files changed, 2 deletions(-)

Patch

--- a/arch/mips/mm/pgtable-32.c~mips-do-not-call-flush_tlb_all-when-setting-pmd-entry
+++ a/arch/mips/mm/pgtable-32.c
@@ -45,7 +45,6 @@  void set_pmd_at(struct mm_struct *mm, un
 		pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
-	flush_tlb_all();
 }
 #endif /* defined(CONFIG_TRANSPARENT_HUGEPAGE) */
 
--- a/arch/mips/mm/pgtable-64.c~mips-do-not-call-flush_tlb_all-when-setting-pmd-entry
+++ a/arch/mips/mm/pgtable-64.c
@@ -100,7 +100,6 @@  void set_pmd_at(struct mm_struct *mm, un
 		pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
-	flush_tlb_all();
 }
 
 void __init pagetable_init(void)