mm/page_owner.c

   1 #include <linux/debugfs.h>
   2 #include <linux/mm.h>
   3 #include <linux/slab.h>
   4 #include <linux/uaccess.h>
   5 #include <linux/bootmem.h>
   6 #include <linux/stacktrace.h>
   7 #include <linux/page_owner.h>
   8 #include "internal.h"
   9
  10 static bool page_owner_disabled = true;
  11 bool page_owner_inited __read_mostly;
  12
  13 static void init_early_allocated_pages(void);
  14
  15 static int early_page_owner_param(char *buf)
  16 {
  17         if (!buf)
  18                 return -EINVAL;
  19
  20         if (strcmp(buf, "on") == 0)
  21                 page_owner_disabled = false;
  22
  23         return 0;
  24 }
  25 early_param("page_owner", early_page_owner_param);
  26
  27 static bool need_page_owner(void)
  28 {
  29         if (page_owner_disabled)
  30                 return false;
  31
  32         return true;
  33 }
  34
  35 static void init_page_owner(void)
  36 {
  37         if (page_owner_disabled)
  38                 return;
  39
  40         page_owner_inited = true;
  41         init_early_allocated_pages();
  42 }
  43
  44 struct page_ext_operations page_owner_ops = {
  45         .need = need_page_owner,
  46         .init = init_page_owner,
  47 };
  48
  49 void __reset_page_owner(struct page *page, unsigned int order)
  50 {
  51         int i;
  52         struct page_ext *page_ext;
  53
  54         for (i = 0; i < (1 << order); i++) {
  55                 page_ext = lookup_page_ext(page + i);
  56                 __clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
  57         }
  58 }
  59
  60 void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
  61 {
  62         struct page_ext *page_ext = lookup_page_ext(page);
  63         struct stack_trace trace = {
  64                 .nr_entries = 0,
  65                 .max_entries = ARRAY_SIZE(page_ext->trace_entries),
  66                 .entries = &page_ext->trace_entries[0],
  67                 .skip = 3,
  68         };
  69
  70         save_stack_trace(&trace);
  71
  72         page_ext->order = order;
  73         page_ext->gfp_mask = gfp_mask;
  74         page_ext->nr_entries = trace.nr_entries;
  75
  76         __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
  77 }
  78
  79 gfp_t __get_page_owner_gfp(struct page *page)
  80 {
  81         struct page_ext *page_ext = lookup_page_ext(page);
  82
  83         return page_ext->gfp_mask;
  84 }
  85
  86 static ssize_t
  87 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
  88                 struct page *page, struct page_ext *page_ext)
  89 {
  90         int ret;
  91         int pageblock_mt, page_mt;
  92         char *kbuf;
  93         struct stack_trace trace = {
  94                 .nr_entries = page_ext->nr_entries,
  95                 .entries = &page_ext->trace_entries[0],
  96         };
  97
  98         kbuf = kmalloc(count, GFP_KERNEL);
  99         if (!kbuf)
 100                 return -ENOMEM;
 101
 102         ret = snprintf(kbuf, count,
 103                         "Page allocated via order %u, mask 0x%x\n",
 104                         page_ext->order, page_ext->gfp_mask);
 105
 106         if (ret >= count)
 107                 goto err;
 108
 109         /* Print information relevant to grouping pages by mobility */
 110         pageblock_mt = get_pfnblock_migratetype(page, pfn);
 111         page_mt  = gfpflags_to_migratetype(page_ext->gfp_mask);
 112         ret += snprintf(kbuf + ret, count - ret,
 113                         "PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
 114                         pfn,
 115                         pfn >> pageblock_order,
 116                         pageblock_mt,
 117                         pageblock_mt != page_mt ? "Fallback" : "        ",
 118                         PageLocked(page)        ? "K" : " ",
 119                         PageError(page)         ? "E" : " ",
 120                         PageReferenced(page)    ? "R" : " ",
 121                         PageUptodate(page)      ? "U" : " ",
 122                         PageDirty(page)         ? "D" : " ",
 123                         PageLRU(page)           ? "L" : " ",
 124                         PageActive(page)        ? "A" : " ",
 125                         PageSlab(page)          ? "S" : " ",
 126                         PageWriteback(page)     ? "W" : " ",
 127                         PageCompound(page)      ? "C" : " ",
 128                         PageSwapCache(page)     ? "B" : " ",
 129                         PageMappedToDisk(page)  ? "M" : " ");
 130
 131         if (ret >= count)
 132                 goto err;
 133
 134         ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
 135         if (ret >= count)
 136                 goto err;
 137
 138         ret += snprintf(kbuf + ret, count - ret, "\n");
 139         if (ret >= count)
 140                 goto err;
 141
 142         if (copy_to_user(buf, kbuf, ret))
 143                 ret = -EFAULT;
 144
 145         kfree(kbuf);
 146         return ret;
 147
 148 err:
 149         kfree(kbuf);
 150         return -ENOMEM;
 151 }
 152
 153 static ssize_t
 154 read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 155 {
 156         unsigned long pfn;
 157         struct page *page;
 158         struct page_ext *page_ext;
 159
 160         if (!page_owner_inited)
 161                 return -EINVAL;
 162
 163         page = NULL;
 164         pfn = min_low_pfn + *ppos;
 165
 166         /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
 167         while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
 168                 pfn++;
 169
 170         drain_all_pages(NULL);
 171
 172         /* Find an allocated page */
 173         for (; pfn < max_pfn; pfn++) {
 174                 /*
 175                  * If the new page is in a new MAX_ORDER_NR_PAGES area,
 176                  * validate the area as existing, skip it if not
 177                  */
 178                 if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
 179                         pfn += MAX_ORDER_NR_PAGES - 1;
 180                         continue;
 181                 }
 182
 183                 /* Check for holes within a MAX_ORDER area */
 184                 if (!pfn_valid_within(pfn))
 185                         continue;
 186
 187                 page = pfn_to_page(pfn);
 188                 if (PageBuddy(page)) {
 189                         unsigned long freepage_order = page_order_unsafe(page);
 190
 191                         if (freepage_order < MAX_ORDER)
 192                                 pfn += (1UL << freepage_order) - 1;
 193                         continue;
 194                 }
 195
 196                 page_ext = lookup_page_ext(page);
 197
 198                 /*
 199                  * Some pages could be missed by concurrent allocation or free,
 200                  * because we don't hold the zone lock.
 201                  */
 202                 if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
 203                         continue;
 204
 205                 /* Record the next PFN to read in the file offset */
 206                 *ppos = (pfn - min_low_pfn) + 1;
 207
 208                 return print_page_owner(buf, count, pfn, page, page_ext);
 209         }
 210
 211         return 0;
 212 }
 213
 214 static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
 215 {
 216         struct page *page;
 217         struct page_ext *page_ext;
 218         unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
 219         unsigned long end_pfn = pfn + zone->spanned_pages;
 220         unsigned long count = 0;
 221
 222         /* Scan block by block. First and last block may be incomplete */
 223         pfn = zone->zone_start_pfn;
 224
 225         /*
 226          * Walk the zone in pageblock_nr_pages steps. If a page block spans
 227          * a zone boundary, it will be double counted between zones. This does
 228          * not matter as the mixed block count will still be correct
 229          */
 230         for (; pfn < end_pfn; ) {
 231                 if (!pfn_valid(pfn)) {
 232                         pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
 233                         continue;
 234                 }
 235
 236                 block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
 237                 block_end_pfn = min(block_end_pfn, end_pfn);
 238
 239                 page = pfn_to_page(pfn);
 240
 241                 for (; pfn < block_end_pfn; pfn++) {
 242                         if (!pfn_valid_within(pfn))
 243                                 continue;
 244
 245                         page = pfn_to_page(pfn);
 246
 247                         /*
 248                          * We are safe to check buddy flag and order, because
 249                          * this is init stage and only single thread runs.
 250                          */
 251                         if (PageBuddy(page)) {
 252                                 pfn += (1UL << page_order(page)) - 1;
 253                                 continue;
 254                         }
 255
 256                         if (PageReserved(page))
 257                                 continue;
 258
 259                         page_ext = lookup_page_ext(page);
 260
 261                         /* Maybe overraping zone */
 262                         if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
 263                                 continue;
 264
 265                         /* Found early allocated page */
 266                         set_page_owner(page, 0, 0);
 267                         count++;
 268                 }
 269         }
 270
 271         pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
 272                 pgdat->node_id, zone->name, count);
 273 }
 274
 275 static void init_zones_in_node(pg_data_t *pgdat)
 276 {
 277         struct zone *zone;
 278         struct zone *node_zones = pgdat->node_zones;
 279         unsigned long flags;
 280
 281         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 282                 if (!populated_zone(zone))
 283                         continue;
 284
 285                 spin_lock_irqsave(&zone->lock, flags);
 286                 init_pages_in_zone(pgdat, zone);
 287                 spin_unlock_irqrestore(&zone->lock, flags);
 288         }
 289 }
 290
 291 static void init_early_allocated_pages(void)
 292 {
 293         pg_data_t *pgdat;
 294
 295         drain_all_pages(NULL);
 296         for_each_online_pgdat(pgdat)
 297                 init_zones_in_node(pgdat);
 298 }
 299
 300 static const struct file_operations proc_page_owner_operations = {
 301         .read           = read_page_owner,
 302 };
 303
 304 static int __init pageowner_init(void)
 305 {
 306         struct dentry *dentry;
 307
 308         if (!page_owner_inited) {
 309                 pr_info("page_owner is disabled\n");
 310                 return 0;
 311         }
 312
 313         dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
 314                         NULL, &proc_page_owner_operations);
 315         if (IS_ERR(dentry))
 316                 return PTR_ERR(dentry);
 317
 318         return 0;
 319 }
 320 late_initcall(pageowner_init)