fs/proc/page.c

   1 #include <linux/bootmem.h>
   2 #include <linux/compiler.h>
   3 #include <linux/fs.h>
   4 #include <linux/init.h>
   5 #include <linux/ksm.h>
   6 #include <linux/mm.h>
   7 #include <linux/mmzone.h>
   8 #include <linux/huge_mm.h>
   9 #include <linux/proc_fs.h>
  10 #include <linux/seq_file.h>
  11 #include <linux/hugetlb.h>
  12 #include <linux/memcontrol.h>
  13 #include <linux/mmu_notifier.h>
  14 #include <linux/page_idle.h>
  15 #include <linux/kernel-page-flags.h>
  16 #include <linux/uaccess.h>
  17 #include "internal.h"
  18
  19 #define KPMSIZE sizeof(u64)
  20 #define KPMMASK (KPMSIZE - 1)
  21 #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
  22
  23 /* /proc/kpagecount - an array exposing page counts
  24  *
  25  * Each entry is a u64 representing the corresponding
  26  * physical page count.
  27  */
  28 static ssize_t kpagecount_read(struct file *file, char __user *buf,
  29                              size_t count, loff_t *ppos)
  30 {
  31         u64 __user *out = (u64 __user *)buf;
  32         struct page *ppage;
  33         unsigned long src = *ppos;
  34         unsigned long pfn;
  35         ssize_t ret = 0;
  36         u64 pcount;
  37
  38         pfn = src / KPMSIZE;
  39         count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
  40         if (src & KPMMASK || count & KPMMASK)
  41                 return -EINVAL;
  42
  43         while (count > 0) {
  44                 if (pfn_valid(pfn))
  45                         ppage = pfn_to_page(pfn);
  46                 else
  47                         ppage = NULL;
  48                 if (!ppage || PageSlab(ppage))
  49                         pcount = 0;
  50                 else
  51                         pcount = page_mapcount(ppage);
  52
  53                 if (put_user(pcount, out)) {
  54                         ret = -EFAULT;
  55                         break;
  56                 }
  57
  58                 pfn++;
  59                 out++;
  60                 count -= KPMSIZE;
  61
  62                 cond_resched();
  63         }
  64
  65         *ppos += (char __user *)out - buf;
  66         if (!ret)
  67                 ret = (char __user *)out - buf;
  68         return ret;
  69 }
  70
  71 static const struct file_operations proc_kpagecount_operations = {
  72         .llseek = mem_lseek,
  73         .read = kpagecount_read,
  74 };
  75
  76 /* /proc/kpageflags - an array exposing page flags
  77  *
  78  * Each entry is a u64 representing the corresponding
  79  * physical page flags.
  80  */
  81
  82 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
  83 {
  84         return ((kflags >> kbit) & 1) << ubit;
  85 }
  86
  87 u64 stable_page_flags(struct page *page)
  88 {
  89         u64 k;
  90         u64 u;
  91
  92         /*
  93          * pseudo flag: KPF_NOPAGE
  94          * it differentiates a memory hole from a page with no flags
  95          */
  96         if (!page)
  97                 return 1 << KPF_NOPAGE;
  98
  99         k = page->flags;
 100         u = 0;
 101
 102         /*
 103          * pseudo flags for the well known (anonymous) memory mapped pages
 104          *
 105          * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
 106          * simple test in page_mapped() is not enough.
 107          */
 108         if (!PageSlab(page) && page_mapped(page))
 109                 u |= 1 << KPF_MMAP;
 110         if (PageAnon(page))
 111                 u |= 1 << KPF_ANON;
 112         if (PageKsm(page))
 113                 u |= 1 << KPF_KSM;
 114
 115         /*
 116          * compound pages: export both head/tail info
 117          * they together define a compound page's start/end pos and order
 118          */
 119         if (PageHead(page))
 120                 u |= 1 << KPF_COMPOUND_HEAD;
 121         if (PageTail(page))
 122                 u |= 1 << KPF_COMPOUND_TAIL;
 123         if (PageHuge(page))
 124                 u |= 1 << KPF_HUGE;
 125         /*
 126          * PageTransCompound can be true for non-huge compound pages (slab
 127          * pages or pages allocated by drivers with __GFP_COMP) because it
 128          * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
 129          * to make sure a given page is a thp, not a non-huge compound page.
 130          */
 131         else if (PageTransCompound(page)) {
 132                 struct page *head = compound_head(page);
 133
 134                 if (PageLRU(head) || PageAnon(head))
 135                         u |= 1 << KPF_THP;
 136                 else if (is_huge_zero_page(head)) {
 137                         u |= 1 << KPF_ZERO_PAGE;
 138                         u |= 1 << KPF_THP;
 139                 }
 140         } else if (is_zero_pfn(page_to_pfn(page)))
 141                 u |= 1 << KPF_ZERO_PAGE;
 142
 143
 144         /*
 145          * Caveats on high order pages: page->_refcount will only be set
 146          * -1 on the head page; SLUB/SLQB do the same for PG_slab;
 147          * SLOB won't set PG_slab at all on compound pages.
 148          */
 149         if (PageBuddy(page))
 150                 u |= 1 << KPF_BUDDY;
 151         else if (page_count(page) == 0 && is_free_buddy_page(page))
 152                 u |= 1 << KPF_BUDDY;
 153
 154         if (PageBalloon(page))
 155                 u |= 1 << KPF_BALLOON;
 156
 157         if (page_is_idle(page))
 158                 u |= 1 << KPF_IDLE;
 159
 160         u |= kpf_copy_bit(k, KPF_LOCKED,        PG_locked);
 161
 162         u |= kpf_copy_bit(k, KPF_SLAB,          PG_slab);
 163         if (PageTail(page) && PageSlab(compound_head(page)))
 164                 u |= 1 << KPF_SLAB;
 165
 166         u |= kpf_copy_bit(k, KPF_ERROR,         PG_error);
 167         u |= kpf_copy_bit(k, KPF_DIRTY,         PG_dirty);
 168         u |= kpf_copy_bit(k, KPF_UPTODATE,      PG_uptodate);
 169         u |= kpf_copy_bit(k, KPF_WRITEBACK,     PG_writeback);
 170
 171         u |= kpf_copy_bit(k, KPF_LRU,           PG_lru);
 172         u |= kpf_copy_bit(k, KPF_REFERENCED,    PG_referenced);
 173         u |= kpf_copy_bit(k, KPF_ACTIVE,        PG_active);
 174         u |= kpf_copy_bit(k, KPF_RECLAIM,       PG_reclaim);
 175
 176         if (PageSwapCache(page))
 177                 u |= 1 << KPF_SWAPCACHE;
 178         u |= kpf_copy_bit(k, KPF_SWAPBACKED,    PG_swapbacked);
 179
 180         u |= kpf_copy_bit(k, KPF_UNEVICTABLE,   PG_unevictable);
 181         u |= kpf_copy_bit(k, KPF_MLOCKED,       PG_mlocked);
 182
 183 #ifdef CONFIG_MEMORY_FAILURE
 184         u |= kpf_copy_bit(k, KPF_HWPOISON,      PG_hwpoison);
 185 #endif
 186
 187 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 188         u |= kpf_copy_bit(k, KPF_UNCACHED,      PG_uncached);
 189 #endif
 190
 191         u |= kpf_copy_bit(k, KPF_RESERVED,      PG_reserved);
 192         u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,  PG_mappedtodisk);
 193         u |= kpf_copy_bit(k, KPF_PRIVATE,       PG_private);
 194         u |= kpf_copy_bit(k, KPF_PRIVATE_2,     PG_private_2);
 195         u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
 196         u |= kpf_copy_bit(k, KPF_ARCH,          PG_arch_1);
 197
 198         return u;
 199 };
 200
 201 static ssize_t kpageflags_read(struct file *file, char __user *buf,
 202                              size_t count, loff_t *ppos)
 203 {
 204         u64 __user *out = (u64 __user *)buf;
 205         struct page *ppage;
 206         unsigned long src = *ppos;
 207         unsigned long pfn;
 208         ssize_t ret = 0;
 209
 210         pfn = src / KPMSIZE;
 211         count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
 212         if (src & KPMMASK || count & KPMMASK)
 213                 return -EINVAL;
 214
 215         while (count > 0) {
 216                 if (pfn_valid(pfn))
 217                         ppage = pfn_to_page(pfn);
 218                 else
 219                         ppage = NULL;
 220
 221                 if (put_user(stable_page_flags(ppage), out)) {
 222                         ret = -EFAULT;
 223                         break;
 224                 }
 225
 226                 pfn++;
 227                 out++;
 228                 count -= KPMSIZE;
 229
 230                 cond_resched();
 231         }
 232
 233         *ppos += (char __user *)out - buf;
 234         if (!ret)
 235                 ret = (char __user *)out - buf;
 236         return ret;
 237 }
 238
 239 static const struct file_operations proc_kpageflags_operations = {
 240         .llseek = mem_lseek,
 241         .read = kpageflags_read,
 242 };
 243
 244 #ifdef CONFIG_MEMCG
 245 static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
 246                                 size_t count, loff_t *ppos)
 247 {
 248         u64 __user *out = (u64 __user *)buf;
 249         struct page *ppage;
 250         unsigned long src = *ppos;
 251         unsigned long pfn;
 252         ssize_t ret = 0;
 253         u64 ino;
 254
 255         pfn = src / KPMSIZE;
 256         count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
 257         if (src & KPMMASK || count & KPMMASK)
 258                 return -EINVAL;
 259
 260         while (count > 0) {
 261                 if (pfn_valid(pfn))
 262                         ppage = pfn_to_page(pfn);
 263                 else
 264                         ppage = NULL;
 265
 266                 if (ppage)
 267                         ino = page_cgroup_ino(ppage);
 268                 else
 269                         ino = 0;
 270
 271                 if (put_user(ino, out)) {
 272                         ret = -EFAULT;
 273                         break;
 274                 }
 275
 276                 pfn++;
 277                 out++;
 278                 count -= KPMSIZE;
 279
 280                 cond_resched();
 281         }
 282
 283         *ppos += (char __user *)out - buf;
 284         if (!ret)
 285                 ret = (char __user *)out - buf;
 286         return ret;
 287 }
 288
 289 static const struct file_operations proc_kpagecgroup_operations = {
 290         .llseek = mem_lseek,
 291         .read = kpagecgroup_read,
 292 };
 293 #endif /* CONFIG_MEMCG */
 294
 295 static int __init proc_page_init(void)
 296 {
 297         proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 298         proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 299 #ifdef CONFIG_MEMCG
 300         proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);
 301 #endif
 302         return 0;
 303 }
 304 fs_initcall(proc_page_init);