diff options
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/Makefile | 2 | ||||
| -rw-r--r-- | Documentation/vm/balance | 18 | ||||
| -rw-r--r-- | Documentation/vm/page-types.c | 698 | ||||
| -rw-r--r-- | Documentation/vm/pagemap.txt | 68 |
4 files changed, 773 insertions, 13 deletions
diff --git a/Documentation/vm/Makefile b/Documentation/vm/Makefile index 6f562f778b28..5bd269b3731a 100644 --- a/Documentation/vm/Makefile +++ b/Documentation/vm/Makefile @@ -2,7 +2,7 @@ obj- := dummy.o # List of programs to build -hostprogs-y := slabinfo +hostprogs-y := slabinfo page-types # Tell kbuild to always build the programs always := $(hostprogs-y) diff --git a/Documentation/vm/balance b/Documentation/vm/balance index bd3d31bc4915..c46e68cf9344 100644 --- a/Documentation/vm/balance +++ b/Documentation/vm/balance @@ -75,15 +75,15 @@ Page stealing from process memory and shm is done if stealing the page would alleviate memory pressure on any zone in the page's node that has fallen below its watermark. -pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are -per-zone fields, used to determine when a zone needs to be balanced. When -the number of pages falls below pages_min, the hysteric field low_on_memory -gets set. This stays set till the number of free pages becomes pages_high. -When low_on_memory is set, page allocation requests will try to free some -pages in the zone (providing GFP_WAIT is set in the request). Orthogonal -to this, is the decision to poke kswapd to free some zone pages. That -decision is not hysteresis based, and is done when the number of free -pages is below pages_low; in which case zone_wake_kswapd is also set. +watemark[WMARK_MIN/WMARK_LOW/WMARK_HIGH]/low_on_memory/zone_wake_kswapd: These +are per-zone fields, used to determine when a zone needs to be balanced. When +the number of pages falls below watermark[WMARK_MIN], the hysteric field +low_on_memory gets set. This stays set till the number of free pages becomes +watermark[WMARK_HIGH]. When low_on_memory is set, page allocation requests will +try to free some pages in the zone (providing GFP_WAIT is set in the request). +Orthogonal to this, is the decision to poke kswapd to free some zone pages. +That decision is not hysteresis based, and is done when the number of free +pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set. (Good) Ideas that I have heard: diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c new file mode 100644 index 000000000000..0833f44ba16b --- /dev/null +++ b/Documentation/vm/page-types.c @@ -0,0 +1,698 @@ +/* + * page-types: Tool for querying page flags + * + * Copyright (C) 2009 Intel corporation + * Copyright (C) 2009 Wu Fengguang <fengguang.wu@intel.com> + */ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <stdint.h> +#include <stdarg.h> +#include <string.h> +#include <getopt.h> +#include <limits.h> +#include <sys/types.h> +#include <sys/errno.h> +#include <sys/fcntl.h> + + +/* + * kernel page flags + */ + +#define KPF_BYTES 8 +#define PROC_KPAGEFLAGS "/proc/kpageflags" + +/* copied from kpageflags_read() */ +#define KPF_LOCKED 0 +#define KPF_ERROR 1 +#define KPF_REFERENCED 2 +#define KPF_UPTODATE 3 +#define KPF_DIRTY 4 +#define KPF_LRU 5 +#define KPF_ACTIVE 6 +#define KPF_SLAB 7 +#define KPF_WRITEBACK 8 +#define KPF_RECLAIM 9 +#define KPF_BUDDY 10 + +/* [11-20] new additions in 2.6.31 */ +#define KPF_MMAP 11 +#define KPF_ANON 12 +#define KPF_SWAPCACHE 13 +#define KPF_SWAPBACKED 14 +#define KPF_COMPOUND_HEAD 15 +#define KPF_COMPOUND_TAIL 16 +#define KPF_HUGE 17 +#define KPF_UNEVICTABLE 18 +#define KPF_NOPAGE 20 + +/* [32-] kernel hacking assistances */ +#define KPF_RESERVED 32 +#define KPF_MLOCKED 33 +#define KPF_MAPPEDTODISK 34 +#define KPF_PRIVATE 35 +#define KPF_PRIVATE_2 36 +#define KPF_OWNER_PRIVATE 37 +#define KPF_ARCH 38 +#define KPF_UNCACHED 39 + +/* [48-] take some arbitrary free slots for expanding overloaded flags + * not part of kernel API + */ +#define KPF_READAHEAD 48 +#define KPF_SLOB_FREE 49 +#define KPF_SLUB_FROZEN 50 +#define KPF_SLUB_DEBUG 51 + +#define KPF_ALL_BITS ((uint64_t)~0ULL) +#define KPF_HACKERS_BITS (0xffffULL << 32) +#define KPF_OVERLOADED_BITS (0xffffULL << 48) +#define BIT(name) (1ULL << KPF_##name) +#define BITS_COMPOUND (BIT(COMPOUND_HEAD) | BIT(COMPOUND_TAIL)) + +static char *page_flag_names[] = { + [KPF_LOCKED] = "L:locked", + [KPF_ERROR] = "E:error", + [KPF_REFERENCED] = "R:referenced", + [KPF_UPTODATE] = "U:uptodate", + [KPF_DIRTY] = "D:dirty", + [KPF_LRU] = "l:lru", + [KPF_ACTIVE] = "A:active", + [KPF_SLAB] = "S:slab", + [KPF_WRITEBACK] = "W:writeback", + [KPF_RECLAIM] = "I:reclaim", + [KPF_BUDDY] = "B:buddy", + + [KPF_MMAP] = "M:mmap", + [KPF_ANON] = "a:anonymous", + [KPF_SWAPCACHE] = "s:swapcache", + [KPF_SWAPBACKED] = "b:swapbacked", + [KPF_COMPOUND_HEAD] = "H:compound_head", + [KPF_COMPOUND_TAIL] = "T:compound_tail", + [KPF_HUGE] = "G:huge", + [KPF_UNEVICTABLE] = "u:unevictable", + [KPF_NOPAGE] = "n:nopage", + + [KPF_RESERVED] = "r:reserved", + [KPF_MLOCKED] = "m:mlocked", + [KPF_MAPPEDTODISK] = "d:mappedtodisk", + [KPF_PRIVATE] = "P:private", + [KPF_PRIVATE_2] = "p:private_2", + [KPF_OWNER_PRIVATE] = "O:owner_private", + [KPF_ARCH] = "h:arch", + [KPF_UNCACHED] = "c:uncached", + + [KPF_READAHEAD] = "I:readahead", + [KPF_SLOB_FREE] = "P:slob_free", + [KPF_SLUB_FROZEN] = "A:slub_frozen", + [KPF_SLUB_DEBUG] = "E:slub_debug", +}; + + +/* + * data structures + */ + +static int opt_raw; /* for kernel developers */ +static int opt_list; /* list pages (in ranges) */ +static int opt_no_summary; /* don't show summary */ +static pid_t opt_pid; /* process to walk */ + +#define MAX_ADDR_RANGES 1024 +static int nr_addr_ranges; +static unsigned long opt_offset[MAX_ADDR_RANGES]; +static unsigned long opt_size[MAX_ADDR_RANGES]; + +#define MAX_BIT_FILTERS 64 +static int nr_bit_filters; +static uint64_t opt_mask[MAX_BIT_FILTERS]; +static uint64_t opt_bits[MAX_BIT_FILTERS]; + +static int page_size; + +#define PAGES_BATCH (64 << 10) /* 64k pages */ +static int kpageflags_fd; +static uint64_t kpageflags_buf[KPF_BYTES * PAGES_BATCH]; + +#define HASH_SHIFT 13 +#define HASH_SIZE (1 << HASH_SHIFT) +#define HASH_MASK (HASH_SIZE - 1) +#define HASH_KEY(flags) (flags & HASH_MASK) + +static unsigned long total_pages; +static unsigned long nr_pages[HASH_SIZE]; +static uint64_t page_flags[HASH_SIZE]; + + +/* + * helper functions + */ + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + +#define min_t(type, x, y) ({ \ + type __min1 = (x); \ + type __min2 = (y); \ + __min1 < __min2 ? __min1 : __min2; }) + +unsigned long pages2mb(unsigned long pages) +{ + return (pages * page_size) >> 20; +} + +void fatal(const char *x, ...) +{ + va_list ap; + + va_start(ap, x); + vfprintf(stderr, x, ap); + va_end(ap); + exit(EXIT_FAILURE); +} + + +/* + * page flag names + */ + +char *page_flag_name(uint64_t flags) +{ + static char buf[65]; + int present; + int i, j; + + for (i = 0, j = 0; i < ARRAY_SIZE(page_flag_names); i++) { + present = (flags >> i) & 1; + if (!page_flag_names[i]) { + if (present) + fatal("unkown flag bit %d\n", i); + continue; + } + buf[j++] = present ? page_flag_names[i][0] : '_'; + } + + return buf; +} + +char *page_flag_longname(uint64_t flags) +{ + static char buf[1024]; + int i, n; + + for (i = 0, n = 0; i < ARRAY_SIZE(page_flag_names); i++) { + if (!page_flag_names[i]) + continue; + if ((flags >> i) & 1) + n += snprintf(buf + n, sizeof(buf) - n, "%s,", + page_flag_names[i] + 2); + } + if (n) + n--; + buf[n] = '\0'; + + return buf; +} + + +/* + * page list and summary + */ + +void show_page_range(unsigned long offset, uint64_t flags) +{ + static uint64_t flags0; + static unsigned long index; + static unsigned long count; + + if (flags == flags0 && offset == index + count) { + count++; + return; + } + + if (count) + printf("%lu\t%lu\t%s\n", + index, count, page_flag_name(flags0)); + + flags0 = flags; + index = offset; + count = 1; +} + +void show_page(unsigned long offset, uint64_t flags) +{ + printf("%lu\t%s\n", offset, page_flag_name(flags)); +} + +void show_summary(void) +{ + int i; + + printf(" flags\tpage-count MB" + " symbolic-flags\t\t\tlong-symbolic-flags\n"); + + for (i = 0; i < ARRAY_SIZE(nr_pages); i++) { + if (nr_pages[i]) + printf("0x%016llx\t%10lu %8lu %s\t%s\n", + (unsigned long long)page_flags[i], + nr_pages[i], + pages2mb(nr_pages[i]), + page_flag_name(page_flags[i]), + page_flag_longname(page_flags[i])); + } + + printf(" total\t%10lu %8lu\n", + total_pages, pages2mb(total_pages)); +} + + +/* + * page flag filters + */ + +int bit_mask_ok(uint64_t flags) +{ + int i; + + for (i = 0; i < nr_bit_filters; i++) { + if (opt_bits[i] == KPF_ALL_BITS) { + if ((flags & opt_mask[i]) == 0) + return 0; + } else { + if ((flags & opt_mask[i]) != opt_bits[i]) + return 0; + } + } + + return 1; +} + +uint64_t expand_overloaded_flags(uint64_t flags) +{ + /* SLOB/SLUB overload several page flags */ + if (flags & BIT(SLAB)) { + if (flags & BIT(PRIVATE)) + flags ^= BIT(PRIVATE) | BIT(SLOB_FREE); + if (flags & BIT(ACTIVE)) + flags ^= BIT(ACTIVE) | BIT(SLUB_FROZEN); + if (flags & BIT(ERROR)) + flags ^= BIT(ERROR) | BIT(SLUB_DEBUG); + } + + /* PG_reclaim is overloaded as PG_readahead in the read path */ + if ((flags & (BIT(RECLAIM) | BIT(WRITEBACK))) == BIT(RECLAIM)) + flags ^= BIT(RECLAIM) | BIT(READAHEAD); + + return flags; +} + +uint64_t well_known_flags(uint64_t flags) +{ + /* hide flags intended only for kernel hacker */ + flags &= ~KPF_HACKERS_BITS; + + /* hide non-hugeTLB compound pages */ + if ((flags & BITS_COMPOUND) && !(flags & BIT(HUGE))) + flags &= ~BITS_COMPOUND; + + return flags; +} + + +/* + * page frame walker + */ + +int hash_slot(uint64_t flags) +{ + int k = HASH_KEY(flags); + int i; + + /* Explicitly reserve slot 0 for flags 0: the following logic + * cannot distinguish an unoccupied slot from slot (flags==0). + */ + if (flags == 0) + return 0; + + /* search through the remaining (HASH_SIZE-1) slots */ + for (i = 1; i < ARRAY_SIZE(page_flags); i++, k++) { + if (!k || k >= ARRAY_SIZE(page_flags)) + k = 1; + if (page_flags[k] == 0) { + page_flags[k] = flags; + return k; + } + if (page_flags[k] == flags) + return k; + } + + fatal("hash table full: bump up HASH_SHIFT?\n"); + exit(EXIT_FAILURE); +} + +void add_page(unsigned long offset, uint64_t flags) +{ + flags = expand_overloaded_flags(flags); + + if (!opt_raw) + flags = well_known_flags(flags); + + if (!bit_mask_ok(flags)) + return; + + if (opt_list == 1) + show_page_range(offset, flags); + else if (opt_list == 2) + show_page(offset, flags); + + nr_pages[hash_slot(flags)]++; + total_pages++; +} + +void walk_pfn(unsigned long index, unsigned long count) +{ + unsigned long batch; + unsigned long n; + unsigned long i; + + if (index > ULONG_MAX / KPF_BYTES) + fatal("index overflow: %lu\n", index); + + lseek(kpageflags_fd, index * KPF_BYTES, SEEK_SET); + + while (count) { + batch = min_t(unsigned long, count, PAGES_BATCH); + n = read(kpageflags_fd, kpageflags_buf, batch * KPF_BYTES); + if (n == 0) + break; + if (n < 0) { + perror(PROC_KPAGEFLAGS); + exit(EXIT_FAILURE); + } + + if (n % KPF_BYTES != 0) + fatal("partial read: %lu bytes\n", n); + n = n / KPF_BYTES; + + for (i = 0; i < n; i++) + add_page(index + i, kpageflags_buf[i]); + + index += batch; + count -= batch; + } +} + +void walk_addr_ranges(void) +{ + int i; + + kpageflags_fd = open(PROC_KPAGEFLAGS, O_RDONLY); + if (kpageflags_fd < 0) { + perror(PROC_KPAGEFLAGS); + exit(EXIT_FAILURE); + } + + if (!nr_addr_ranges) + walk_pfn(0, ULONG_MAX); + + for (i = 0; i < nr_addr_ranges; i++) + walk_pfn(opt_offset[i], opt_size[i]); + + close(kpageflags_fd); +} + + +/* + * user interface + */ + +const char *page_flag_type(uint64_t flag) +{ + if (flag & KPF_HACKERS_BITS) + return "(r)"; + if (flag & KPF_OVERLOADED_BITS) + return "(o)"; + return " "; +} + +void usage(void) +{ + int i, j; + + printf( +"page-types [options]\n" +" -r|--raw Raw mode, for kernel developers\n" +" -a|--addr addr-spec Walk a range of pages\n" +" -b|--bits bits-spec Walk pages with specified bits\n" +#if 0 /* planned features */ +" -p|--pid pid Walk process address space\n" +" -f|--file filename Walk file address space\n" +#endif +" -l|--list Show page details in ranges\n" +" -L|--list-each Show page details one by one\n" +" -N|--no-summary Don't show summay info\n" +" -h|--help Show this usage message\n" +"addr-spec:\n" +" N one page at offset N (unit: pages)\n" +" N+M pages range from N to N+M-1\n" +" N,M pages range from N to M-1\n" +" N, pages range from N to end\n" +" ,M pages range from 0 to M\n" +"bits-spec:\n" +" bit1,bit2 (flags & (bit1|bit2)) != 0\n" +" bit1,bit2=bit1 (flags & (bit1|bit2)) == bit1\n" +" bit1,~bit2 (flags & (bit1|bit2)) == bit1\n" +" =bit1,bit2 flags == (bit1|bit2)\n" +"bit-names:\n" + ); + + for (i = 0, j = 0; i < ARRAY_SIZE(page_flag_names); i++) { + if (!page_flag_names[i]) + continue; + printf("%16s%s", page_flag_names[i] + 2, + page_flag_type(1ULL << i)); + if (++j > 3) { + j = 0; + putchar('\n'); + } + } + printf("\n " + "(r) raw mode bits (o) overloaded bits\n"); +} + +unsigned long long parse_number(const char *str) +{ + unsigned long long n; + + n = strtoll(str, NULL, 0); + + if (n == 0 && str[0] != '0') + fatal("invalid name or number: %s\n", str); + + return n; +} + +void parse_pid(const char *str) +{ + opt_pid = parse_number(str); +} + +void parse_file(const char *name) +{ +} + +void add_addr_range(unsigned long offset, unsigned long size) +{ + if (nr_addr_ranges >= MAX_ADDR_RANGES) + fatal("too much addr ranges\n"); + + opt_offset[nr_addr_ranges] = offset; + opt_size[nr_addr_ranges] = size; + nr_addr_ranges++; +} + +void parse_addr_range(const char *optarg) +{ + unsigned long offset; + unsigned long size; + char *p; + + p = strchr(optarg, ','); + if (!p) + p = strchr(optarg, '+'); + + if (p == optarg) { + offset = 0; + size = parse_number(p + 1); + } else if (p) { + offset = parse_number(optarg); + if (p[1] == '\0') + size = ULONG_MAX; + else { + size = parse_number(p + 1); + if (*p == ',') { + if (size < offset) + fatal("invalid range: %lu,%lu\n", + offset, size); + size -= offset; + } + } + } else { + offset = parse_number(optarg); + size = 1; + } + + add_addr_range(offset, size); +} + +void add_bits_filter(uint64_t mask, uint64_t bits) +{ + if (nr_bit_filters >= MAX_BIT_FILTERS) + fatal("too much bit filters\n"); + + opt_mask[nr_bit_filters] = mask; + opt_bits[nr_bit_filters] = bits; + nr_bit_filters++; +} + +uint64_t parse_flag_name(const char *str, int len) +{ + int i; + + if (!*str || !len) + return 0; + + if (len <= 8 && !strncmp(str, "compound", len)) + return BITS_COMPOUND; + + for (i = 0; i < ARRAY_SIZE(page_flag_names); i++) { + if (!page_flag_names[i]) + continue; + if (!strncmp(str, page_flag_names[i] + 2, len)) + return 1ULL << i; + } + + return parse_number(str); +} + +uint64_t parse_flag_names(const char *str, int all) +{ + const char *p = str; + uint64_t flags = 0; + + while (1) { + if (*p == ',' || *p == '=' || *p == '\0') { + if ((*str != '~') || (*str == '~' && all && *++str)) + flags |= parse_flag_name(str, p - str); + if (*p != ',') + break; + str = p + 1; + } + p++; + } + + return flags; +} + +void parse_bits_mask(const char *optarg) +{ + uint64_t mask; + uint64_t bits; + const char *p; + + p = strchr(optarg, '='); + if (p == optarg) { + mask = KPF_ALL_BITS; + bits = parse_flag_names(p + 1, 0); + } else if (p) { + mask = parse_flag_names(optarg, 0); + bits = parse_flag_names(p + 1, 0); + } else if (strchr(optarg, '~')) { + mask = parse_flag_names(optarg, 1); + bits = parse_flag_names(optarg, 0); + } else { + mask = parse_flag_names(optarg, 0); + bits = KPF_ALL_BITS; + } + + add_bits_filter(mask, bits); +} + + +struct option opts[] = { + { "raw" , 0, NULL, 'r' }, + { "pid" , 1, NULL, 'p' }, + { "file" , 1, NULL, 'f' }, + { "addr" , 1, NULL, 'a' }, + { "bits" , 1, NULL, 'b' }, + { "list" , 0, NULL, 'l' }, + { "list-each" , 0, NULL, 'L' }, + { "no-summary", 0, NULL, 'N' }, + { "help" , 0, NULL, 'h' }, + { NULL , 0, NULL, 0 } +}; + +int main(int argc, char *argv[]) +{ + int c; + + page_size = getpagesize(); + + while ((c = getopt_long(argc, argv, + "rp:f:a:b:lLNh", opts, NULL)) != -1) { + switch (c) { + case 'r': + opt_raw = 1; + break; + case 'p': + parse_pid(optarg); + break; + case 'f': + parse_file(optarg); + break; + case 'a': + parse_addr_range(optarg); + break; + case 'b': + parse_bits_mask(optarg); + break; + case 'l': + opt_list = 1; + break; + case 'L': + opt_list = 2; + break; + case 'N': + opt_no_summary = 1; + break; + case 'h': + usage(); + exit(0); + default: + usage(); + exit(1); + } + } + + if (opt_list == 1) + printf("offset\tcount\tflags\n"); + if (opt_list == 2) + printf("offset\tflags\n"); + + walk_addr_ranges(); + + if (opt_list == 1) + show_page_range(0, 0); /* drain the buffer */ + + if (opt_no_summary) + return 0; + + if (opt_list) + printf("\n\n"); + + show_summary(); + + return 0; +} diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt index ce72c0fe6177..600a304a828c 100644 --- a/Documentation/vm/pagemap.txt +++ b/Documentation/vm/pagemap.txt @@ -12,9 +12,9 @@ There are three components to pagemap: value for each virtual page, containing the following data (from fs/proc/task_mmu.c, above pagemap_read): - * Bits 0-55 page frame number (PFN) if present + * Bits 0-54 page frame number (PFN) if present * Bits 0-4 swap type if swapped - * Bits 5-55 swap offset if swapped + * Bits 5-54 swap offset if swapped * Bits 55-60 page shift (page size = 1<<page shift) * Bit 61 reserved for future use * Bit 62 page swapped @@ -36,7 +36,7 @@ There are three components to pagemap: * /proc/kpageflags. This file contains a 64-bit set of flags for each page, indexed by PFN. - The flags are (from fs/proc/proc_misc, above kpageflags_read): + The flags are (from fs/proc/page.c, above kpageflags_read): 0. LOCKED 1. ERROR @@ -49,6 +49,68 @@ There are three components to pagemap: 8. WRITEBACK 9. RECLAIM 10. BUDDY + 11. MMAP + 12. ANON + 13. SWAPCACHE + 14. SWAPBACKED + 15. COMPOUND_HEAD + 16. COMPOUND_TAIL + 16. HUGE + 18. UNEVICTABLE + 20. NOPAGE + +Short descriptions to the page flags: + + 0. LOCKED + page is being locked for exclusive access, eg. by undergoing read/write IO + + 7. SLAB + page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator + When compound page is used, SLUB/SLQB will only set this flag on the head + page; SLOB will not flag it at all. + +10. BUDDY + a free memory block managed by the buddy system allocator + The buddy system organizes free memory in blocks of various orders. + An order N block has 2^N physically contiguous pages, with the BUDDY flag + set for and _only_ for the first page. + +15. COMPOUND_HEAD +16. COMPOUND_TAIL + A compound page with order N consists of 2^N physically contiguous pages. + A compound page with order 2 takes the form of "HTTT", where H donates its + head page and T donates its tail page(s). The major consumers of compound + pages are hugeTLB pages (Documentation/vm/hugetlbpage.txt), the SLUB etc. + memory allocators and various device drivers. However in this interface, + only huge/giga pages are made visible to end users. +17. HUGE + this is an integral part of a HugeTLB page + +20. NOPAGE + no page frame exists at the requested address + + [IO related page flags] + 1. ERROR IO error occurred + 3. UPTODATE page has up-to-date data + ie. for file backed page: (in-memory data revision >= on-disk one) + 4. DIRTY page has been written to, hence contains new data + ie. for file backed page: (in-memory data revision > on-disk one) + 8. WRITEBACK page is being synced to disk + + [LRU related page flags] + 5. LRU page is in one of the LRU lists + 6. ACTIVE page is in the active LRU list +18. UNEVICTABLE page is in the unevictable (non-)LRU list + It is somehow pinned and not a candidate for LRU page reclaims, + eg. ramfs pages, shmctl(SHM_LOCK) and mlock() memory segments + 2. REFERENCED page has been referenced since last LRU list enqueue/requeue + 9. RECLAIM page will be reclaimed soon after its pageout IO completed +11. MMAP a memory mapped page +12. ANON a memory mapped page that is not part of a file +13. SWAPCACHE page is mapped to swap space, ie. has an associated swap entry +14. SWAPBACKED page is backed by swap/RAM + +The page-types tool in this directory can be used to query the above flags. Using pagemap to do something useful: |
