From 12ebc1581ad114543ae822aa3a12f76072e2f902 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Fri, 20 Feb 2015 10:36:28 +0530 Subject: [PATCH] mm,thp: introduce flush_pmd_tlb_range ARCHes with special requirements for evicting THP backing TLB entries can implement this. Otherwise also, it can help optimize TLB flush in THP regime. stock flush_tlb_range() typically has optimization to nuke the entire TLB if flush span is greater than a certain threshhold, which will likely be true for a single huge page. Thus a single thp flush will invalidate the entrire TLB which is not desirable. e.g. see arch/arc: flush_pmd_tlb_range Acked-by: Kirill A. Shutemov Link: http://lkml.kernel.org/r/20151009100816.GC7873@node Signed-off-by: Vineet Gupta --- mm/huge_memory.c | 2 +- mm/pgtable-generic.c | 26 ++++++++++++++++++++------ 2 files changed, 21 insertions(+), 7 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4b06b8db9df2..e25eb3d2081a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1880,7 +1880,7 @@ static int __split_huge_page_map(struct page *page, * here). But it is generally safer to never allow * small and huge TLB entries for the same virtual * address to be loaded simultaneously. So instead of - * doing "pmd_populate(); flush_tlb_range();" we first + * doing "pmd_populate(); flush_pmd_tlb_range();" we first * mark the current pmd notpresent (atomically because * here the pmd_trans_huge and pmd_trans_splitting * must remain set at all times on the pmd until the diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c index c9c59bb75a17..7d3db0247983 100644 --- a/mm/pgtable-generic.c +++ b/mm/pgtable-generic.c @@ -84,6 +84,20 @@ pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, #ifdef CONFIG_TRANSPARENT_HUGEPAGE +#ifndef __HAVE_ARCH_FLUSH_PMD_TLB_RANGE + +/* + * ARCHes with special requirements for evicting THP backing TLB entries can + * implement this. Otherwise also, it can help optimize normal TLB flush in + * THP regime. stock flush_tlb_range() typically has optimization to nuke the + * entire TLB TLB if flush span is greater than a threshhold, which will + * likely be true for a single huge page. Thus a single thp flush will + * invalidate the entire TLB which is not desitable. + * e.g. see arch/arc: flush_pmd_tlb_range + */ +#define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) +#endif + #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp, @@ -93,7 +107,7 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, VM_BUG_ON(address & ~HPAGE_PMD_MASK); if (changed) { set_pmd_at(vma->vm_mm, address, pmdp, entry); - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); } return changed; } @@ -107,7 +121,7 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma, VM_BUG_ON(address & ~HPAGE_PMD_MASK); young = pmdp_test_and_clear_young(vma, address, pmdp); if (young) - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return young; } #endif @@ -120,7 +134,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address, VM_BUG_ON(address & ~HPAGE_PMD_MASK); VM_BUG_ON(!pmd_trans_huge(*pmdp)); pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return pmd; } #endif @@ -133,7 +147,7 @@ void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, VM_BUG_ON(address & ~HPAGE_PMD_MASK); set_pmd_at(vma->vm_mm, address, pmdp, pmd); /* tlb flush only to serialize against gup-fast */ - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); } #endif @@ -179,7 +193,7 @@ void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address, { pmd_t entry = *pmdp; set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(entry)); - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); } #endif @@ -196,7 +210,7 @@ pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address, VM_BUG_ON(address & ~HPAGE_PMD_MASK); VM_BUG_ON(pmd_trans_huge(*pmdp)); pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp); - flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE); + flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE); return pmd; } #endif -- GitLab