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authorBibo Mao <maobibo@loongson.cn>2020-05-27 05:25:19 +0300
committerThomas Bogendoerfer <tsbogend@alpha.franken.de>2020-05-27 14:06:40 +0300
commit44bf431b47b4298d8aaba7b02d0ad29fc609a03c (patch)
treeabdc24c53f8a9c2a7c283e799a44c29db145d780
parent7df676974359f927056b882e10a5b24d2033169b (diff)
downloadlinux-44bf431b47b4298d8aaba7b02d0ad29fc609a03c.tar.xz
mm/memory.c: Add memory read privilege on page fault handling
Here add pte_sw_mkyoung function to make page readable on MIPS platform during page fault handling. This patch improves page fault latency about 10% on my MIPS machine with lmbench lat_pagefault case. It is noop function on other arches, there is no negative influence on those architectures. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
-rw-r--r--arch/mips/include/asm/pgtable.h2
-rw-r--r--include/asm-generic/pgtable.h16
-rw-r--r--mm/memory.c3
3 files changed, 21 insertions, 0 deletions
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 6f40612b3152..d9772aff2f02 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -414,6 +414,8 @@ static inline pte_t pte_mkyoung(pte_t pte)
return pte;
}
+#define pte_sw_mkyoung pte_mkyoung
+
#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
static inline int pte_huge(pte_t pte) { return pte_val(pte) & _PAGE_HUGE; }
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index fa5c73ff8226..b5278ec627db 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -244,6 +244,22 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
}
#endif
+/*
+ * On some architectures hardware does not set page access bit when accessing
+ * memory page, it is responsibilty of software setting this bit. It brings
+ * out extra page fault penalty to track page access bit. For optimization page
+ * access bit can be set during all page fault flow on these arches.
+ * To be differentiate with macro pte_mkyoung, this macro is used on platforms
+ * where software maintains page access bit.
+ */
+#ifndef pte_sw_mkyoung
+static inline pte_t pte_sw_mkyoung(pte_t pte)
+{
+ return pte;
+}
+#define pte_sw_mkyoung pte_sw_mkyoung
+#endif
+
#ifndef pte_savedwrite
#define pte_savedwrite pte_write
#endif
diff --git a/mm/memory.c b/mm/memory.c
index 8bb31c4d94d0..c7c8960bdd1e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2704,6 +2704,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
}
flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
entry = mk_pte(new_page, vma->vm_page_prot);
+ entry = pte_sw_mkyoung(entry);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/*
* Clear the pte entry and flush it first, before updating the
@@ -3378,6 +3379,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
__SetPageUptodate(page);
entry = mk_pte(page, vma->vm_page_prot);
+ entry = pte_sw_mkyoung(entry);
if (vma->vm_flags & VM_WRITE)
entry = pte_mkwrite(pte_mkdirty(entry));
@@ -3660,6 +3662,7 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
flush_icache_page(vma, page);
entry = mk_pte(page, vma->vm_page_prot);
+ entry = pte_sw_mkyoung(entry);
if (write)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/* copy-on-write page */