A dax-huge-page mapping while it uses some thp helpers is ultimately not a
transparent huge page. The distinction is especially important in the
get_user_pages() path. pmd_devmap() is used to distinguish dax-pmds from
pmd_huge() and pmd_trans_huge() which have slightly different semantics.
Explicitly mark the pmd_trans_huge() helpers that dax needs by adding
pmd_devmap() checks.
Also, before we introduce usages of pmd_pfn() in common code, include a
definition for archs that have not needed it to date.
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
arch/ia64/include/asm/pgtable.h | 1 +
arch/sh/include/asm/pgtable-3level.h | 1 +
arch/x86/include/asm/pgtable.h | 2 +-
include/linux/huge_mm.h | 3 ++-
mm/huge_memory.c | 23 +++++++++++++----------
mm/memory.c | 8 ++++----
6 files changed, 22 insertions(+), 16 deletions(-)
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 9f3ed9ee8f13..81d2af23958f 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -273,6 +273,7 @@ extern unsigned long VMALLOC_END;
#define pmd_clear(pmdp) (pmd_val(*(pmdp)) = 0UL)
#define pmd_page_vaddr(pmd) ((unsigned long) __va(pmd_val(pmd) & _PFN_MASK))
#define pmd_page(pmd) virt_to_page((pmd_val(pmd) + PAGE_OFFSET))
+#define pmd_pfn(pmd) (pmd_val(pmd) >> PAGE_SHIFT)
#define pud_none(pud) (!pud_val(pud))
#define pud_bad(pud) (!ia64_phys_addr_valid(pud_val(pud)))
diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 249a985d9648..bb29a80fb40e 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -29,6 +29,7 @@
typedef struct { unsigned long long pmd; } pmd_t;
#define pmd_val(x) ((x).pmd)
+#define pmd_pfn(x) ((pmd_val(x) & PMD_MASK) >> PAGE_SHIFT)
#define __pmd(x) ((pmd_t) { (x) } )
static inline unsigned long pud_page_vaddr(pud_t pud)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 02096a5dec2a..d5747ada2a76 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -178,7 +178,7 @@ static inline int pmd_trans_splitting(pmd_t pmd)
static inline int pmd_trans_huge(pmd_t pmd)
{
- return pmd_val(pmd) & _PAGE_PSE;
+ return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
}
static inline int has_transparent_hugepage(void)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index d218abedfeb9..9c9c1688889a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -105,7 +105,8 @@ extern void __split_huge_page_pmd(struct vm_area_struct *vma,
#define split_huge_page_pmd(__vma, __address, __pmd) \
do { \
pmd_t *____pmd = (__pmd); \
- if (unlikely(pmd_trans_huge(*____pmd))) \
+ if (unlikely(pmd_trans_huge(*____pmd) \
+ || pmd_devmap(*____pmd))) \
__split_huge_page_pmd(__vma, __address, \
____pmd); \
} while (0)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6b506df659ec..329cedf48b8a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -933,7 +933,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
ret = -EAGAIN;
pmd = *src_pmd;
- if (unlikely(!pmd_trans_huge(pmd))) {
+ if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
pte_free(dst_mm, pgtable);
goto out_unlock;
}
@@ -965,17 +965,20 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
goto out;
}
- src_page = pmd_page(pmd);
- VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
- get_page(src_page);
- page_dup_rmap(src_page);
- add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ if (pmd_trans_huge(pmd)) {
+ /* thp accounting separate from pmd_devmap accounting */
+ src_page = pmd_page(pmd);
+ VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+ get_page(src_page);
+ page_dup_rmap(src_page);
+ add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+ pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+ atomic_long_inc(&dst_mm->nr_ptes);
+ }
pmdp_set_wrprotect(src_mm, addr, src_pmd);
pmd = pmd_mkold(pmd_wrprotect(pmd));
- pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
set_pmd_at(dst_mm, addr, dst_pmd, pmd);
- atomic_long_inc(&dst_mm->nr_ptes);
ret = 0;
out_unlock:
@@ -1599,7 +1602,7 @@ int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl)
{
*ptl = pmd_lock(vma->vm_mm, pmd);
- if (likely(pmd_trans_huge(*pmd))) {
+ if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) {
if (unlikely(pmd_trans_splitting(*pmd))) {
spin_unlock(*ptl);
wait_split_huge_page(vma->anon_vma, pmd);
@@ -2975,7 +2978,7 @@ void __split_huge_page_pmd(struct vm_area_struct *vma, unsigned long address,
again:
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
ptl = pmd_lock(mm, pmd);
- if (unlikely(!pmd_trans_huge(*pmd)))
+ if (unlikely(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
goto unlock;
if (vma_is_dax(vma)) {
pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
diff --git a/mm/memory.c b/mm/memory.c
index 6a34be836a3b..5b9c6bab80d1 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -961,7 +961,7 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
src_pmd = pmd_offset(src_pud, addr);
do {
next = pmd_addr_end(addr, end);
- if (pmd_trans_huge(*src_pmd)) {
+ if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
int err;
VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
err = copy_huge_pmd(dst_mm, src_mm,
@@ -1193,7 +1193,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
- if (pmd_trans_huge(*pmd)) {
+ if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE) {
#ifdef CONFIG_DEBUG_VM
if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
@@ -3366,7 +3366,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
int ret;
barrier();
- if (pmd_trans_huge(orig_pmd)) {
+ if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
unsigned int dirty = flags & FAULT_FLAG_WRITE;
/*
@@ -3403,7 +3403,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unlikely(__pte_alloc(mm, vma, pmd, address)))
return VM_FAULT_OOM;
/* if an huge pmd materialized from under us just retry later */
- if (unlikely(pmd_trans_huge(*pmd)))
+ if (unlikely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
return 0;
/*
* A regular pmd is established and it can't morph into a huge pmd
--
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