On 04/23/2015 11:03 PM, Kirill A. Shutemov wrote:
With new refcounting we don't need to mark PMDs splitting. Let's drop code
to handle this.

Arch-specific code will removed separately.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
Tested-by: Sasha Levin <sasha.le...@oracle.com>

Acked-by: Vlastimil Babka <vba...@suse.cz>

Some functions could be changed to return bool instead of int:
pmd_trans_huge_lock()
__pmd_trans_huge_lock()
move_huge_pmd()

And there's some leftover references to pmd_trans_splitting()
include/asm-generic/pgtable.h:static inline int pmd_trans_splitting(pmd_t pmd)
(for the !TRANSPARENT_HUGEPAGE config)

mm/gup.c:               if (pmd_none(pmd) || pmd_trans_splitting(pmd))


---
  fs/proc/task_mmu.c            |  8 +++----
  include/asm-generic/pgtable.h |  5 ----
  include/linux/huge_mm.h       |  9 --------
  mm/gup.c                      |  7 ------
  mm/huge_memory.c              | 54 ++++++++-----------------------------------
  mm/memcontrol.c               | 14 ++---------
  mm/memory.c                   | 18 ++-------------
  mm/mincore.c                  |  2 +-
  mm/pgtable-generic.c          | 14 -----------
  mm/rmap.c                     |  4 +---
  10 files changed, 20 insertions(+), 115 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 95bc384ee3f7..edd63c40ed71 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -534,7 +534,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, 
unsigned long end,
        pte_t *pte;
        spinlock_t *ptl;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                smaps_pmd_entry(pmd, addr, walk);
                spin_unlock(ptl);
                return 0;
@@ -799,7 +799,7 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long 
addr,
        spinlock_t *ptl;
        struct page *page;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
                        clear_soft_dirty_pmd(vma, addr, pmd);
                        goto out;
@@ -1112,7 +1112,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long 
addr, unsigned long end,
        pte_t *pte, *orig_pte;
        int err = 0;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                int pmd_flags2;

                if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
@@ -1416,7 +1416,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long 
addr,
        pte_t *orig_pte;
        pte_t *pte;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                pte_t huge_pte = *(pte_t *)pmd;
                struct page *page;

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 39f1d6a2b04d..fe617b7e4be6 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -184,11 +184,6 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  #endif

-#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-extern void pmdp_splitting_flush(struct vm_area_struct *vma,
-                                unsigned long address, pmd_t *pmdp);
-#endif
-
  #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
  extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
                                       pgtable_t pgtable);
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 47f80207782f..0382230b490f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -49,15 +49,9 @@ enum transparent_hugepage_flag {
  #endif
  };

-enum page_check_address_pmd_flag {
-       PAGE_CHECK_ADDRESS_PMD_FLAG,
-       PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG,
-       PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG,
-};
  extern pmd_t *page_check_address_pmd(struct page *page,
                                     struct mm_struct *mm,
                                     unsigned long address,
-                                    enum page_check_address_pmd_flag flag,
                                     spinlock_t **ptl);
  extern int pmd_freeable(pmd_t pmd);

@@ -102,7 +96,6 @@ extern unsigned long transparent_hugepage_flags;
  #define split_huge_page(page) BUILD_BUG()
  #define split_huge_pmd(__vma, __pmd, __address) BUILD_BUG()

-#define wait_split_huge_page(__anon_vma, __pmd) BUILD_BUG();
  #if HPAGE_PMD_ORDER >= MAX_ORDER
  #error "hugepages can't be allocated by the buddy allocator"
  #endif
@@ -169,8 +162,6 @@ static inline int split_huge_page(struct page *page)
  {
        return 0;
  }
-#define wait_split_huge_page(__anon_vma, __pmd)        \
-       do { } while (0)
  #define split_huge_pmd(__vma, __pmd, __address)       \
        do { } while (0)
  static inline int hugepage_madvise(struct vm_area_struct *vma,
diff --git a/mm/gup.c b/mm/gup.c
index 53f9681b7b30..0cebfa76fd0c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -207,13 +207,6 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
                spin_unlock(ptl);
                return follow_page_pte(vma, address, pmd, flags);
        }
-
-       if (unlikely(pmd_trans_splitting(*pmd))) {
-               spin_unlock(ptl);
-               wait_split_huge_page(vma->anon_vma, pmd);
-               return follow_page_pte(vma, address, pmd, flags);
-       }
-
        if (flags & FOLL_SPLIT) {
                int ret;
                page = pmd_page(*pmd);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 16c6c262385c..23181f836b62 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -889,15 +889,6 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct 
mm_struct *src_mm,
                goto out_unlock;
        }

-       if (unlikely(pmd_trans_splitting(pmd))) {
-               /* split huge page running from under us */
-               spin_unlock(src_ptl);
-               spin_unlock(dst_ptl);
-               pte_free(dst_mm, pgtable);
-
-               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);
@@ -1403,7 +1394,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct 
vm_area_struct *vma,
        spinlock_t *ptl;
        int ret = 0;

-       if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (__pmd_trans_huge_lock(pmd, vma, &ptl)) {
                struct page *page;
                pgtable_t pgtable;
                pmd_t orig_pmd;
@@ -1443,7 +1434,6 @@ int move_huge_pmd(struct vm_area_struct *vma, struct 
vm_area_struct *new_vma,
                  pmd_t *old_pmd, pmd_t *new_pmd)
  {
        spinlock_t *old_ptl, *new_ptl;
-       int ret = 0;
        pmd_t pmd;

        struct mm_struct *mm = vma->vm_mm;
@@ -1452,7 +1442,7 @@ int move_huge_pmd(struct vm_area_struct *vma, struct 
vm_area_struct *new_vma,
            (new_addr & ~HPAGE_PMD_MASK) ||
            old_end - old_addr < HPAGE_PMD_SIZE ||
            (new_vma->vm_flags & VM_NOHUGEPAGE))
-               goto out;
+               return 0;

        /*
         * The destination pmd shouldn't be established, free_pgtables()
@@ -1460,15 +1450,14 @@ int move_huge_pmd(struct vm_area_struct *vma, struct 
vm_area_struct *new_vma,
         */
        if (WARN_ON(!pmd_none(*new_pmd))) {
                VM_BUG_ON(pmd_trans_huge(*new_pmd));
-               goto out;
+               return 0;
        }

        /*
         * We don't have to worry about the ordering of src and dst
         * ptlocks because exclusive mmap_sem prevents deadlock.
         */
-       ret = __pmd_trans_huge_lock(old_pmd, vma, &old_ptl);
-       if (ret == 1) {
+       if (__pmd_trans_huge_lock(old_pmd, vma, &old_ptl)) {
                new_ptl = pmd_lockptr(mm, new_pmd);
                if (new_ptl != old_ptl)
                        spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING);
@@ -1484,9 +1473,9 @@ int move_huge_pmd(struct vm_area_struct *vma, struct 
vm_area_struct *new_vma,
                if (new_ptl != old_ptl)
                        spin_unlock(new_ptl);
                spin_unlock(old_ptl);
+               return 1;
        }
-out:
-       return ret;
+       return 0;
  }

  /*
@@ -1502,7 +1491,7 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t 
*pmd,
        spinlock_t *ptl;
        int ret = 0;

-       if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (__pmd_trans_huge_lock(pmd, vma, &ptl)) {
                pmd_t entry;
                bool preserve_write = prot_numa && pmd_write(*pmd);
                ret = 1;
@@ -1543,17 +1532,8 @@ 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 (unlikely(pmd_trans_splitting(*pmd))) {
-                       spin_unlock(*ptl);
-                       wait_split_huge_page(vma->anon_vma, pmd);
-                       return -1;
-               } else {
-                       /* Thp mapped by 'pmd' is stable, so we can
-                        * handle it as it is. */
-                       return 1;
-               }
-       }
+       if (likely(pmd_trans_huge(*pmd)))
+               return 1;
        spin_unlock(*ptl);
        return 0;
  }
@@ -1569,7 +1549,6 @@ int __pmd_trans_huge_lock(pmd_t *pmd, struct 
vm_area_struct *vma,
  pmd_t *page_check_address_pmd(struct page *page,
                              struct mm_struct *mm,
                              unsigned long address,
-                             enum page_check_address_pmd_flag flag,
                              spinlock_t **ptl)
  {
        pgd_t *pgd;
@@ -1592,21 +1571,8 @@ pmd_t *page_check_address_pmd(struct page *page,
                goto unlock;
        if (pmd_page(*pmd) != page)
                goto unlock;
-       /*
-        * split_vma() may create temporary aliased mappings. There is
-        * no risk as long as all huge pmd are found and have their
-        * splitting bit set before __split_huge_page_refcount
-        * runs. Finding the same huge pmd more than once during the
-        * same rmap walk is not a problem.
-        */
-       if (flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
-           pmd_trans_splitting(*pmd))
-               goto unlock;
-       if (pmd_trans_huge(*pmd)) {
-               VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
-                         !pmd_trans_splitting(*pmd));
+       if (pmd_trans_huge(*pmd))
                return pmd;
-       }
  unlock:
        spin_unlock(*ptl);
        return NULL;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f659d4f77138..1bc6a77067ad 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4888,7 +4888,7 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t 
*pmd,
        pte_t *pte;
        spinlock_t *ptl;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
                        mc.precharge += HPAGE_PMD_NR;
                spin_unlock(ptl);
@@ -5056,17 +5056,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
        union mc_target target;
        struct page *page;

-       /*
-        * We don't take compound_lock() here but no race with splitting thp
-        * happens because:
-        *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
-        *    under splitting, which means there's no concurrent thp split,
-        *  - if another thread runs into split_huge_page() just after we
-        *    entered this if-block, the thread must wait for page table lock
-        *    to be unlocked in __split_huge_page_splitting(), where the main
-        *    part of thp split is not executed yet.
-        */
-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                if (mc.precharge < HPAGE_PMD_NR) {
                        spin_unlock(ptl);
                        return 0;
diff --git a/mm/memory.c b/mm/memory.c
index 61e7ed722760..1bad3766b00c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -565,7 +565,6 @@ int __pte_alloc(struct mm_struct *mm, struct vm_area_struct 
*vma,
  {
        spinlock_t *ptl;
        pgtable_t new = pte_alloc_one(mm, address);
-       int wait_split_huge_page;
        if (!new)
                return -ENOMEM;

@@ -585,18 +584,14 @@ int __pte_alloc(struct mm_struct *mm, struct 
vm_area_struct *vma,
        smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

        ptl = pmd_lock(mm, pmd);
-       wait_split_huge_page = 0;
        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
                atomic_long_inc(&mm->nr_ptes);
                pmd_populate(mm, pmd, new);
                new = NULL;
-       } else if (unlikely(pmd_trans_splitting(*pmd)))
-               wait_split_huge_page = 1;
+       }
        spin_unlock(ptl);
        if (new)
                pte_free(mm, new);
-       if (wait_split_huge_page)
-               wait_split_huge_page(vma->anon_vma, pmd);
        return 0;
  }

@@ -612,8 +607,7 @@ int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
        if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
                pmd_populate_kernel(&init_mm, pmd, new);
                new = NULL;
-       } else
-               VM_BUG_ON(pmd_trans_splitting(*pmd));
+       }
        spin_unlock(&init_mm.page_table_lock);
        if (new)
                pte_free_kernel(&init_mm, new);
@@ -3299,14 +3293,6 @@ static int __handle_mm_fault(struct mm_struct *mm, 
struct vm_area_struct *vma,
                if (pmd_trans_huge(orig_pmd)) {
                        unsigned int dirty = flags & FAULT_FLAG_WRITE;

-                       /*
-                        * If the pmd is splitting, return and retry the
-                        * the fault.  Alternative: wait until the split
-                        * is done, and goto retry.
-                        */
-                       if (pmd_trans_splitting(orig_pmd))
-                               return 0;
-
                        if (pmd_protnone(orig_pmd))
                                return do_huge_pmd_numa_page(mm, vma, address,
                                                             orig_pmd, pmd);
diff --git a/mm/mincore.c b/mm/mincore.c
index be25efde64a4..feb867f5fdf4 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -117,7 +117,7 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long 
addr, unsigned long end,
        unsigned char *vec = walk->private;
        int nr = (end - addr) >> PAGE_SHIFT;

-       if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+       if (pmd_trans_huge_lock(pmd, vma, &ptl)) {
                memset(vec, 1, nr);
                spin_unlock(ptl);
                goto out;
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index c25f94b33811..2fe699cedd4d 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -133,20 +133,6 @@ pmd_t pmdp_clear_flush(struct vm_area_struct *vma, 
unsigned long address,
  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  #endif

-#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
-                         pmd_t *pmdp)
-{
-       pmd_t pmd = pmd_mksplitting(*pmdp);
-       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);
-}
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-#endif
-
  #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
diff --git a/mm/rmap.c b/mm/rmap.c
index 4ca4b5cffd95..1636a96e5f71 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -737,8 +737,7 @@ static int page_referenced_one(struct page *page, struct 
vm_area_struct *vma,
                 * rmap might return false positives; we must filter
                 * these out using page_check_address_pmd().
                 */
-               pmd = page_check_address_pmd(page, mm, address,
-                                            PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
+               pmd = page_check_address_pmd(page, mm, address, &ptl);
                if (!pmd)
                        return SWAP_AGAIN;

@@ -748,7 +747,6 @@ static int page_referenced_one(struct page *page, struct 
vm_area_struct *vma,
                        return SWAP_FAIL; /* To break the loop */
                }

-               /* go ahead even if the pmd is pmd_trans_splitting() */
                if (pmdp_clear_flush_young_notify(vma, address, pmd))
                        referenced++;



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to