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