target/linux/generic/backport-6.1/020-v6.3-17-UPSTREAM-mm-multi-gen-LRU-improve-walk_pmd_range.patch

   1 From fc0e3b06e0f19917b7ecad7967a72f61d4743644 Mon Sep 17 00:00:00 2001
   2 From: "T.J. Alumbaugh" <talumbau@google.com>
   3 Date: Wed, 18 Jan 2023 00:18:26 +0000
   4 Subject: [PATCH 17/19] UPSTREAM: mm: multi-gen LRU: improve walk_pmd_range()
   5
   6 Improve readability of walk_pmd_range() and walk_pmd_range_locked().
   7
   8 Link: https://lkml.kernel.org/r/20230118001827.1040870-7-talumbau@google.com
   9 Change-Id: Ia084fbf53fe989673b7804ca8ca520af12d7d52a
  10 Signed-off-by: T.J. Alumbaugh <talumbau@google.com>
  11 Cc: Yu Zhao <yuzhao@google.com>
  12 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  13 (cherry picked from commit b5ff4133617d0eced35b685da0bd0929dd9fabb7)
  14 Bug: 274865848
  15 Signed-off-by: T.J. Mercier <tjmercier@google.com>
  16 ---
  17  mm/vmscan.c | 40 ++++++++++++++++++++--------------------
  18  1 file changed, 20 insertions(+), 20 deletions(-)
  19
  20 --- a/mm/vmscan.c
  21 +++ b/mm/vmscan.c
  22 @@ -3980,8 +3980,8 @@ restart:
  23  }
  24
  25  #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG)
  26 -static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area_struct *vma,
  27 -                                 struct mm_walk *args, unsigned long *bitmap, unsigned long *start)
  28 +static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area_struct *vma,
  29 +                                 struct mm_walk *args, unsigned long *bitmap, unsigned long *first)
  30  {
  31         int i;
  32         pmd_t *pmd;
  33 @@ -3994,18 +3994,19 @@ static void walk_pmd_range_locked(pud_t
  34         VM_WARN_ON_ONCE(pud_leaf(*pud));
  35
  36         /* try to batch at most 1+MIN_LRU_BATCH+1 entries */
  37 -       if (*start == -1) {
  38 -               *start = next;
  39 +       if (*first == -1) {
  40 +               *first = addr;
  41 +               bitmap_zero(bitmap, MIN_LRU_BATCH);
  42                 return;
  43         }
  44
  45 -       i = next == -1 ? 0 : pmd_index(next) - pmd_index(*start);
  46 +       i = addr == -1 ? 0 : pmd_index(addr) - pmd_index(*first);
  47         if (i && i <= MIN_LRU_BATCH) {
  48                 __set_bit(i - 1, bitmap);
  49                 return;
  50         }
  51
  52 -       pmd = pmd_offset(pud, *start);
  53 +       pmd = pmd_offset(pud, *first);
  54
  55         ptl = pmd_lockptr(args->mm, pmd);
  56         if (!spin_trylock(ptl))
  57 @@ -4016,15 +4017,16 @@ static void walk_pmd_range_locked(pud_t
  58         do {
  59                 unsigned long pfn;
  60                 struct folio *folio;
  61 -               unsigned long addr = i ? (*start & PMD_MASK) + i * PMD_SIZE : *start;
  62 +
  63 +               /* don't round down the first address */
  64 +               addr = i ? (*first & PMD_MASK) + i * PMD_SIZE : *first;
  65
  66                 pfn = get_pmd_pfn(pmd[i], vma, addr);
  67                 if (pfn == -1)
  68                         goto next;
  69
  70                 if (!pmd_trans_huge(pmd[i])) {
  71 -                       if (arch_has_hw_nonleaf_pmd_young() &&
  72 -                           get_cap(LRU_GEN_NONLEAF_YOUNG))
  73 +                       if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG))
  74                                 pmdp_test_and_clear_young(vma, addr, pmd + i);
  75                         goto next;
  76                 }
  77 @@ -4053,12 +4055,11 @@ next:
  78         arch_leave_lazy_mmu_mode();
  79         spin_unlock(ptl);
  80  done:
  81 -       *start = -1;
  82 -       bitmap_zero(bitmap, MIN_LRU_BATCH);
  83 +       *first = -1;
  84  }
  85  #else
  86 -static void walk_pmd_range_locked(pud_t *pud, unsigned long next, struct vm_area_struct *vma,
  87 -                                 struct mm_walk *args, unsigned long *bitmap, unsigned long *start)
  88 +static void walk_pmd_range_locked(pud_t *pud, unsigned long addr, struct vm_area_struct *vma,
  89 +                                 struct mm_walk *args, unsigned long *bitmap, unsigned long *first)
  90  {
  91  }
  92  #endif
  93 @@ -4071,9 +4072,9 @@ static void walk_pmd_range(pud_t *pud, u
  94         unsigned long next;
  95         unsigned long addr;
  96         struct vm_area_struct *vma;
  97 -       unsigned long pos = -1;
  98 +       unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)];
  99 +       unsigned long first = -1;
 100         struct lru_gen_mm_walk *walk = args->private;
 101 -       unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {};
 102
 103         VM_WARN_ON_ONCE(pud_leaf(*pud));
 104
 105 @@ -4115,18 +4116,17 @@ restart:
 106                         if (pfn < pgdat->node_start_pfn || pfn >= pgdat_end_pfn(pgdat))
 107                                 continue;
 108
 109 -                       walk_pmd_range_locked(pud, addr, vma, args, bitmap, &pos);
 110 +                       walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
 111                         continue;
 112                 }
 113  #endif
 114                 walk->mm_stats[MM_NONLEAF_TOTAL]++;
 115
 116 -               if (arch_has_hw_nonleaf_pmd_young() &&
 117 -                   get_cap(LRU_GEN_NONLEAF_YOUNG)) {
 118 +               if (arch_has_hw_nonleaf_pmd_young() && get_cap(LRU_GEN_NONLEAF_YOUNG)) {
 119                         if (!pmd_young(val))
 120                                 continue;
 121
 122 -                       walk_pmd_range_locked(pud, addr, vma, args, bitmap, &pos);
 123 +                       walk_pmd_range_locked(pud, addr, vma, args, bitmap, &first);
 124                 }
 125
 126                 if (!walk->force_scan && !test_bloom_filter(walk->lruvec, walk->max_seq, pmd + i))
 127 @@ -4143,7 +4143,7 @@ restart:
 128                 update_bloom_filter(walk->lruvec, walk->max_seq + 1, pmd + i);
 129         }
 130
 131 -       walk_pmd_range_locked(pud, -1, vma, args, bitmap, &pos);
 132 +       walk_pmd_range_locked(pud, -1, vma, args, bitmap, &first);
 133
 134         if (i < PTRS_PER_PMD && get_next_vma(PUD_MASK, PMD_SIZE, args, &start, &end))
 135                 goto restart;