The patch titled
Subject: thp: Prepare for DAX huge pages
has been added to the -mm tree. Its filename is
thp-prepare-for-dax-huge-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/thp-prepare-for-dax-huge-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/thp-prepare-for-dax-huge-pages.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Subject: thp: Prepare for DAX huge pages
Add a vma_is_dax() helper macro to test whether the VMA is DAX, and use it
in zap_huge_pmd() and __split_huge_page_pmd().
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Cc: Hillf Danton <dhillf@xxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/dax.h | 4 +++
mm/huge_memory.c | 45 +++++++++++++++++++++++++-----------------
2 files changed, 31 insertions(+), 18 deletions(-)
diff -puN include/linux/dax.h~thp-prepare-for-dax-huge-pages include/linux/dax.h
--- a/include/linux/dax.h~thp-prepare-for-dax-huge-pages
+++ a/include/linux/dax.h
@@ -18,4 +18,8 @@ int dax_pfn_mkwrite(struct vm_area_struc
#define dax_mkwrite(vma, vmf, gb, iod) dax_fault(vma, vmf, gb, iod)
#define __dax_mkwrite(vma, vmf, gb, iod) __dax_fault(vma, vmf, gb, iod)
+static inline bool vma_is_dax(struct vm_area_struct *vma)
+{
+ return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
+}
#endif
diff -puN mm/huge_memory.c~thp-prepare-for-dax-huge-pages mm/huge_memory.c
--- a/mm/huge_memory.c~thp-prepare-for-dax-huge-pages
+++ a/mm/huge_memory.c
@@ -1418,7 +1418,6 @@ int zap_huge_pmd(struct mmu_gather *tlb,
int ret = 0;
if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
- struct page *page;
pgtable_t pgtable;
pmd_t orig_pmd;
/*
@@ -1430,13 +1429,22 @@ int zap_huge_pmd(struct mmu_gather *tlb,
orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
tlb->fullmm);
tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
- pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+ if (vma_is_dax(vma)) {
+ if (is_huge_zero_pmd(orig_pmd)) {
+ pgtable = NULL;
+ } else {
+ spin_unlock(ptl);
+ return 1;
+ }
+ } else {
+ pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
+ }
if (is_huge_zero_pmd(orig_pmd)) {
atomic_long_dec(&tlb->mm->nr_ptes);
spin_unlock(ptl);
put_huge_zero_page();
} else {
- page = pmd_page(orig_pmd);
+ struct page *page = pmd_page(orig_pmd);
page_remove_rmap(page);
VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
@@ -1445,7 +1453,8 @@ int zap_huge_pmd(struct mmu_gather *tlb,
spin_unlock(ptl);
tlb_remove_page(tlb, page);
}
- pte_free(tlb->mm, pgtable);
+ if (pgtable)
+ pte_free(tlb->mm, pgtable);
ret = 1;
}
return ret;
@@ -2916,7 +2925,7 @@ void __split_huge_page_pmd(struct vm_are
pmd_t *pmd)
{
spinlock_t *ptl;
- struct page *page;
+ struct page *page = NULL;
struct mm_struct *mm = vma->vm_mm;
unsigned long haddr = address & HPAGE_PMD_MASK;
unsigned long mmun_start; /* For mmu_notifiers */
@@ -2929,25 +2938,25 @@ void __split_huge_page_pmd(struct vm_are
again:
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
ptl = pmd_lock(mm, pmd);
- if (unlikely(!pmd_trans_huge(*pmd))) {
- spin_unlock(ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- return;
- }
- if (is_huge_zero_pmd(*pmd)) {
+ if (unlikely(!pmd_trans_huge(*pmd)))
+ goto unlock;
+ if (vma_is_dax(vma)) {
+ pmdp_huge_clear_flush(vma, haddr, pmd);
+ } else if (is_huge_zero_pmd(*pmd)) {
__split_huge_zero_page_pmd(vma, haddr, pmd);
- spin_unlock(ptl);
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- return;
+ } else {
+ page = pmd_page(*pmd);
+ VM_BUG_ON_PAGE(!page_count(page), page);
+ get_page(page);
}
- page = pmd_page(*pmd);
- VM_BUG_ON_PAGE(!page_count(page), page);
- get_page(page);
+ unlock:
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
- split_huge_page(page);
+ if (!page)
+ return;
+ split_huge_page(page);
put_page(page);
/*
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxxxx are
mm-make-gup-handle-pfn-mapping-unless-foll_get-is-requested.patch
dax-move-dax-related-functions-to-a-new-header.patch
thp-prepare-for-dax-huge-pages.patch
mm-add-a-pmd_fault-handler.patch
mm-export-various-functions-for-the-benefit-of-dax.patch
mm-add-vmf_insert_pfn_pmd.patch
dax-add-huge-page-fault-support.patch
ext2-huge-page-fault-support.patch
ext4-huge-page-fault-support.patch
xfs-huge-page-fault-support.patch
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