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 <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20151009100816.GC7873@node
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index c9c59bb..7d3db02 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -84,6 +84,20 @@
#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 @@
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 @@
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 @@
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 @@
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 @@
{
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 @@
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