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mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd 

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.

[kirill.shutemov@linux.intel.com: fix regression in handling mlocked pages in  __split_huge_pmd()]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2016-01-15 16:56:52 -08:00 committed by Linus Torvalds
parent 5c2c2587b1
commit 5c7fb56e5e
7 changed files with 47 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
arch/x86/include/asm/pgtable.h
View File

@ -164,13 +164,20 @@ static inline int pmd_large(pmd_t pte)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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)
{
return cpu_has_pse;
}
#ifdef __HAVE_ARCH_PTE_DEVMAP
static inline int pmd_devmap(pmd_t pmd)
{
return !!(pmd_val(pmd) & _PAGE_DEVMAP);
}
#endif
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline pte_t pte_set_flags(pte_t pte, pteval_t set)

5
include/linux/huge_mm.h
View File

@ -104,7 +104,8 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
#define split_huge_pmd(__vma, __pmd, __address) \
do { \
pmd_t *____pmd = (__pmd); \
if (pmd_trans_huge(*____pmd)) \
if (pmd_trans_huge(*____pmd) \
|| pmd_devmap(*____pmd)) \
__split_huge_pmd(__vma, __pmd, __address); \
} while (0)
@ -124,7 +125,7 @@ static inline bool pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
spinlock_t **ptl)
{
VM_BUG_ON_VMA(!rwsem_is_locked(&vma->vm_mm->mmap_sem), vma);
if (pmd_trans_huge(*pmd))
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd))
return __pmd_trans_huge_lock(pmd, vma, ptl);
else
return false;

7
include/linux/mm.h
View File

@ -329,6 +329,13 @@ struct inode;
#define page_private(page) ((page)->private)
#define set_page_private(page, v) ((page)->private = (v))
#if !defined(__HAVE_ARCH_PTE_DEVMAP) || !defined(CONFIG_TRANSPARENT_HUGEPAGE)
static inline int pmd_devmap(pmd_t pmd)
{
return 0;
}
#endif
/*
* FIXME: take this include out, include page-flags.h in
* files which need it (119 of them)

38
mm/huge_memory.c
View File

@ -995,7 +995,7 @@ 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;
}
@ -1018,17 +1018,20 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
goto out_unlock;
}
src_page = pmd_page(pmd);
VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
get_page(src_page);
page_dup_rmap(src_page, true);
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, true);
add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
atomic_long_inc(&dst_mm->nr_ptes);
pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
}
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:
@ -1716,7 +1719,7 @@ bool __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)))
return true;
spin_unlock(*ptl);
return false;
@ -2788,7 +2791,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
VM_BUG_ON(!pmd_trans_huge(*pmd));
VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
count_vm_event(THP_SPLIT_PMD);
@ -2901,14 +2904,15 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
ptl = pmd_lock(mm, pmd);
if (unlikely(!pmd_trans_huge(*pmd)))
if (pmd_trans_huge(*pmd)) {
page = pmd_page(*pmd);
if (PageMlocked(page))
get_page(page);
else
page = NULL;
} else if (!pmd_devmap(*pmd))
goto out;
page = pmd_page(*pmd);
__split_huge_pmd_locked(vma, pmd, haddr, false);
if (PageMlocked(page))
get_page(page);
else
page = NULL;
out:
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
@ -2938,7 +2942,7 @@ static void split_huge_pmd_address(struct vm_area_struct *vma,
return;
pmd = pmd_offset(pud, address);
if (!pmd_present(*pmd) || !pmd_trans_huge(*pmd))
if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
return;
/*
* Caller holds the mmap_sem write mode, so a huge pmd cannot

8
mm/memory.c
View File

@ -950,7 +950,7 @@ 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,
@ -1177,7 +1177,7 @@ 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)) {
@ -3375,7 +3375,7 @@ 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;
if (pmd_protnone(orig_pmd))
@ -3404,7 +3404,7 @@ 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

5
mm/mprotect.c
View File

@ -149,7 +149,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
unsigned long this_pages;
next = pmd_addr_end(addr, end);
if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
&& pmd_none_or_clear_bad(pmd))
continue;
/* invoke the mmu notifier if the pmd is populated */
@ -158,7 +159,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
mmu_notifier_invalidate_range_start(mm, mni_start, end);
}
if (pmd_trans_huge(*pmd)) {
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
if (next - addr != HPAGE_PMD_SIZE)
split_huge_pmd(vma, pmd, addr);
else {

2
mm/pgtable-generic.c
View File

@ -132,7 +132,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
{
pmd_t pmd;
VM_BUG_ON(address & ~HPAGE_PMD_MASK);
VM_BUG_ON(!pmd_trans_huge(*pmdp));
VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
return pmd;