swapops-0003-Revert-mm-introduce-page_vma_mapped_walk.patch

   1 From 47a3e75a6d3db759a5fce3e922f144af0d6f1d38 Mon Sep 17 00:00:00 2001
   2 From: Seth Forshee <seth.forshee@canonical.com>
   3 Date: Wed, 3 May 2017 08:34:56 -0500
   4 Subject: [PATCH 3/4] Revert "mm: introduce page_vma_mapped_walk()"
   5
   6 This reverts commit 6e2a092a48d38cfc0f06bdb523014acbfeba7b2e.
   7
   8 Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
   9 ---
  10  include/linux/rmap.h |  26 -------
  11  mm/Makefile          |   6 +-
  12  mm/huge_memory.c     |   9 +--
  13  mm/page_vma_mapped.c | 188 ---------------------------------------------------
  14  4 files changed, 5 insertions(+), 224 deletions(-)
  15  delete mode 100644 mm/page_vma_mapped.c
  16
  17 diff --git a/include/linux/rmap.h b/include/linux/rmap.h
  18 index b76343610653..15321fb1df6b 100644
  19 --- a/include/linux/rmap.h
  20 +++ b/include/linux/rmap.h
  21 @@ -9,7 +9,6 @@
  22  #include <linux/mm.h>
  23  #include <linux/rwsem.h>
  24  #include <linux/memcontrol.h>
  25 -#include <linux/highmem.h>
  26
  27  /*
  28   * The anon_vma heads a list of private "related" vmas, to scan if
  29 @@ -233,31 +232,6 @@ static inline bool page_check_address_transhuge(struct page *page,
  30  }
  31  #endif
  32
  33 -/* Avoid racy checks */
  34 -#define PVMW_SYNC              (1 << 0)
  35 -/* Look for migarion entries rather than present PTEs */
  36 -#define PVMW_MIGRATION         (1 << 1)
  37 -
  38 -struct page_vma_mapped_walk {
  39 -       struct page *page;
  40 -       struct vm_area_struct *vma;
  41 -       unsigned long address;
  42 -       pmd_t *pmd;
  43 -       pte_t *pte;
  44 -       spinlock_t *ptl;
  45 -       unsigned int flags;
  46 -};
  47 -
  48 -static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
  49 -{
  50 -       if (pvmw->pte)
  51 -               pte_unmap(pvmw->pte);
  52 -       if (pvmw->ptl)
  53 -               spin_unlock(pvmw->ptl);
  54 -}
  55 -
  56 -bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
  57 -
  58  /*
  59   * Used by swapoff to help locate where page is expected in vma.
  60   */
  61 diff --git a/mm/Makefile b/mm/Makefile
  62 index 474fa3431059..14fa1c83b504 100644
  63 --- a/mm/Makefile
  64 +++ b/mm/Makefile
  65 @@ -23,10 +23,8 @@ KCOV_INSTRUMENT_vmstat.o := n
  66
  67  mmu-y                  := nommu.o
  68  mmu-$(CONFIG_MMU)      := gup.o highmem.o memory.o mincore.o \
  69 -                          mlock.o mmap.o mprotect.o mremap.o msync.o \
  70 -                          page_vma_mapped.o pagewalk.o pgtable-generic.o \
  71 -                          rmap.o vmalloc.o
  72 -
  73 +                          mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
  74 +                          vmalloc.o pagewalk.o pgtable-generic.o
  75
  76  ifdef CONFIG_CROSS_MEMORY_ATTACH
  77  mmu-$(CONFIG_MMU)      += process_vm_access.o
  78 diff --git a/mm/huge_memory.c b/mm/huge_memory.c
  79 index 87303c6bacf4..e6de801fa477 100644
  80 --- a/mm/huge_memory.c
  81 +++ b/mm/huge_memory.c
  82 @@ -1878,12 +1878,9 @@ static void freeze_page(struct page *page)
  83  static void unfreeze_page(struct page *page)
  84  {
  85         int i;
  86 -       if (PageTransHuge(page)) {
  87 -               remove_migration_ptes(page, page, true);
  88 -       } else {
  89 -               for (i = 0; i < HPAGE_PMD_NR; i++)
  90 -                       remove_migration_ptes(page + i, page + i, true);
  91 -       }
  92 +
  93 +       for (i = 0; i < HPAGE_PMD_NR; i++)
  94 +               remove_migration_ptes(page + i, page + i, true);
  95  }
  96
  97  static void __split_huge_page_tail(struct page *head, int tail,
  98 diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
  99 deleted file mode 100644
 100 index dc1a54826cf2..000000000000
 101 --- a/mm/page_vma_mapped.c
 102 +++ /dev/null
 103 @@ -1,188 +0,0 @@
 104 -#include <linux/mm.h>
 105 -#include <linux/rmap.h>
 106 -#include <linux/hugetlb.h>
 107 -#include <linux/swap.h>
 108 -#include <linux/swapops.h>
 109 -
 110 -#include "internal.h"
 111 -
 112 -static inline bool check_pmd(struct page_vma_mapped_walk *pvmw)
 113 -{
 114 -       pmd_t pmde;
 115 -       /*
 116 -        * Make sure we don't re-load pmd between present and !trans_huge check.
 117 -        * We need a consistent view.
 118 -        */
 119 -       pmde = READ_ONCE(*pvmw->pmd);
 120 -       return pmd_present(pmde) && !pmd_trans_huge(pmde);
 121 -}
 122 -
 123 -static inline bool not_found(struct page_vma_mapped_walk *pvmw)
 124 -{
 125 -       page_vma_mapped_walk_done(pvmw);
 126 -       return false;
 127 -}
 128 -
 129 -static bool map_pte(struct page_vma_mapped_walk *pvmw)
 130 -{
 131 -       pvmw->pte = pte_offset_map(pvmw->pmd, pvmw->address);
 132 -       if (!(pvmw->flags & PVMW_SYNC)) {
 133 -               if (pvmw->flags & PVMW_MIGRATION) {
 134 -                       if (!is_swap_pte(*pvmw->pte))
 135 -                               return false;
 136 -               } else {
 137 -                       if (!pte_present(*pvmw->pte))
 138 -                               return false;
 139 -               }
 140 -       }
 141 -       pvmw->ptl = pte_lockptr(pvmw->vma->vm_mm, pvmw->pmd);
 142 -       spin_lock(pvmw->ptl);
 143 -       return true;
 144 -}
 145 -
 146 -static bool check_pte(struct page_vma_mapped_walk *pvmw)
 147 -{
 148 -       if (pvmw->flags & PVMW_MIGRATION) {
 149 -#ifdef CONFIG_MIGRATION
 150 -               swp_entry_t entry;
 151 -               if (!is_swap_pte(*pvmw->pte))
 152 -                       return false;
 153 -               entry = pte_to_swp_entry(*pvmw->pte);
 154 -               if (!is_migration_entry(entry))
 155 -                       return false;
 156 -               if (migration_entry_to_page(entry) - pvmw->page >=
 157 -                               hpage_nr_pages(pvmw->page)) {
 158 -                       return false;
 159 -               }
 160 -               if (migration_entry_to_page(entry) < pvmw->page)
 161 -                       return false;
 162 -#else
 163 -               WARN_ON_ONCE(1);
 164 -#endif
 165 -       } else {
 166 -               if (!pte_present(*pvmw->pte))
 167 -                       return false;
 168 -
 169 -               /* THP can be referenced by any subpage */
 170 -               if (pte_page(*pvmw->pte) - pvmw->page >=
 171 -                               hpage_nr_pages(pvmw->page)) {
 172 -                       return false;
 173 -               }
 174 -               if (pte_page(*pvmw->pte) < pvmw->page)
 175 -                       return false;
 176 -       }
 177 -
 178 -       return true;
 179 -}
 180 -
 181 -/**
 182 - * page_vma_mapped_walk - check if @pvmw->page is mapped in @pvmw->vma at
 183 - * @pvmw->address
 184 - * @pvmw: pointer to struct page_vma_mapped_walk. page, vma, address and flags
 185 - * must be set. pmd, pte and ptl must be NULL.
 186 - *
 187 - * Returns true if the page is mapped in the vma. @pvmw->pmd and @pvmw->pte point
 188 - * to relevant page table entries. @pvmw->ptl is locked. @pvmw->address is
 189 - * adjusted if needed (for PTE-mapped THPs).
 190 - *
 191 - * If @pvmw->pmd is set but @pvmw->pte is not, you have found PMD-mapped page
 192 - * (usually THP). For PTE-mapped THP, you should run page_vma_mapped_walk() in
 193 - * a loop to find all PTEs that map the THP.
 194 - *
 195 - * For HugeTLB pages, @pvmw->pte is set to the relevant page table entry
 196 - * regardless of which page table level the page is mapped at. @pvmw->pmd is
 197 - * NULL.
 198 - *
 199 - * Retruns false if there are no more page table entries for the page in
 200 - * the vma. @pvmw->ptl is unlocked and @pvmw->pte is unmapped.
 201 - *
 202 - * If you need to stop the walk before page_vma_mapped_walk() returned false,
 203 - * use page_vma_mapped_walk_done(). It will do the housekeeping.
 204 - */
 205 -bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 206 -{
 207 -       struct mm_struct *mm = pvmw->vma->vm_mm;
 208 -       struct page *page = pvmw->page;
 209 -       pgd_t *pgd;
 210 -       pud_t *pud;
 211 -
 212 -       /* The only possible pmd mapping has been handled on last iteration */
 213 -       if (pvmw->pmd && !pvmw->pte)
 214 -               return not_found(pvmw);
 215 -
 216 -       /* Only for THP, seek to next pte entry makes sense */
 217 -       if (pvmw->pte) {
 218 -               if (!PageTransHuge(pvmw->page) || PageHuge(pvmw->page))
 219 -                       return not_found(pvmw);
 220 -               goto next_pte;
 221 -       }
 222 -
 223 -       if (unlikely(PageHuge(pvmw->page))) {
 224 -               /* when pud is not present, pte will be NULL */
 225 -               pvmw->pte = huge_pte_offset(mm, pvmw->address);
 226 -               if (!pvmw->pte)
 227 -                       return false;
 228 -
 229 -               pvmw->ptl = huge_pte_lockptr(page_hstate(page), mm, pvmw->pte);
 230 -               spin_lock(pvmw->ptl);
 231 -               if (!check_pte(pvmw))
 232 -                       return not_found(pvmw);
 233 -               return true;
 234 -       }
 235 -restart:
 236 -       pgd = pgd_offset(mm, pvmw->address);
 237 -       if (!pgd_present(*pgd))
 238 -               return false;
 239 -       pud = pud_offset(pgd, pvmw->address);
 240 -       if (!pud_present(*pud))
 241 -               return false;
 242 -       pvmw->pmd = pmd_offset(pud, pvmw->address);
 243 -       if (pmd_trans_huge(*pvmw->pmd)) {
 244 -               pvmw->ptl = pmd_lock(mm, pvmw->pmd);
 245 -               if (!pmd_present(*pvmw->pmd))
 246 -                       return not_found(pvmw);
 247 -               if (likely(pmd_trans_huge(*pvmw->pmd))) {
 248 -                       if (pvmw->flags & PVMW_MIGRATION)
 249 -                               return not_found(pvmw);
 250 -                       if (pmd_page(*pvmw->pmd) != page)
 251 -                               return not_found(pvmw);
 252 -                       return true;
 253 -               } else {
 254 -                       /* THP pmd was split under us: handle on pte level */
 255 -                       spin_unlock(pvmw->ptl);
 256 -                       pvmw->ptl = NULL;
 257 -               }
 258 -       } else {
 259 -               if (!check_pmd(pvmw))
 260 -                       return false;
 261 -       }
 262 -       if (!map_pte(pvmw))
 263 -               goto next_pte;
 264 -       while (1) {
 265 -               if (check_pte(pvmw))
 266 -                       return true;
 267 -next_pte:      do {
 268 -                       pvmw->address += PAGE_SIZE;
 269 -                       if (pvmw->address >=
 270 -                                       __vma_address(pvmw->page, pvmw->vma) +
 271 -                                       hpage_nr_pages(pvmw->page) * PAGE_SIZE)
 272 -                               return not_found(pvmw);
 273 -                       /* Did we cross page table boundary? */
 274 -                       if (pvmw->address % PMD_SIZE == 0) {
 275 -                               pte_unmap(pvmw->pte);
 276 -                               if (pvmw->ptl) {
 277 -                                       spin_unlock(pvmw->ptl);
 278 -                                       pvmw->ptl = NULL;
 279 -                               }
 280 -                               goto restart;
 281 -                       } else {
 282 -                               pvmw->pte++;
 283 -                       }
 284 -               } while (pte_none(*pvmw->pte));
 285 -
 286 -               if (!pvmw->ptl) {
 287 -                       pvmw->ptl = pte_lockptr(mm, pvmw->pmd);
 288 -                       spin_lock(pvmw->ptl);
 289 -               }
 290 -       }
 291 -}
 292 --
 293 2.7.4
 294