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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-12-14 20:58:45 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 11:53:15 -0500
commit8d69aaee80c123b460918816cbfa2e83224c3646 (patch)
tree899a69417dbd81f9b53926d7076629cc9b394ae5
parent253d553ba75ab26b3e9e2f70cbf6fbf0813f7e86 (diff)
swap_info: swap_map of chars not shorts
Halve the vmalloc'ed swap_map array from unsigned shorts to unsigned chars: it's still very unusual to reach a swap count of 126, and the next patch allows it to be extended indefinitely. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/swap.h8
-rw-r--r--mm/swapfile.c40
2 files changed, 27 insertions, 21 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index c9d8870892b8..f733deb10748 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -151,9 +151,9 @@ enum {
151 151
152#define SWAP_CLUSTER_MAX 32 152#define SWAP_CLUSTER_MAX 32
153 153
154#define SWAP_MAP_MAX 0x7ffe 154#define SWAP_MAP_MAX 0x7e
155#define SWAP_MAP_BAD 0x7fff 155#define SWAP_MAP_BAD 0x7f
156#define SWAP_HAS_CACHE 0x8000 /* There is a swap cache of entry. */ 156#define SWAP_HAS_CACHE 0x80 /* There is a swap cache of entry. */
157 157
158/* 158/*
159 * The in-memory structure used to track swap areas. 159 * The in-memory structure used to track swap areas.
@@ -167,7 +167,7 @@ struct swap_info_struct {
167 struct block_device *bdev; 167 struct block_device *bdev;
168 struct swap_extent first_swap_extent; 168 struct swap_extent first_swap_extent;
169 struct swap_extent *curr_swap_extent; 169 struct swap_extent *curr_swap_extent;
170 unsigned short *swap_map; 170 unsigned char *swap_map;
171 unsigned int lowest_bit; 171 unsigned int lowest_bit;
172 unsigned int highest_bit; 172 unsigned int highest_bit;
173 unsigned int lowest_alloc; /* while preparing discard cluster */ 173 unsigned int lowest_alloc; /* while preparing discard cluster */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 52497490a7ca..c0d7b9ed0c16 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -53,7 +53,7 @@ static struct swap_info_struct *swap_info[MAX_SWAPFILES];
53 53
54static DEFINE_MUTEX(swapon_mutex); 54static DEFINE_MUTEX(swapon_mutex);
55 55
56static inline int swap_count(unsigned short ent) 56static inline unsigned char swap_count(unsigned char ent)
57{ 57{
58 return ent & ~SWAP_HAS_CACHE; 58 return ent & ~SWAP_HAS_CACHE;
59} 59}
@@ -203,7 +203,7 @@ static int wait_for_discard(void *word)
203#define LATENCY_LIMIT 256 203#define LATENCY_LIMIT 256
204 204
205static inline unsigned long scan_swap_map(struct swap_info_struct *si, 205static inline unsigned long scan_swap_map(struct swap_info_struct *si,
206 unsigned short usage) 206 unsigned char usage)
207{ 207{
208 unsigned long offset; 208 unsigned long offset;
209 unsigned long scan_base; 209 unsigned long scan_base;
@@ -531,12 +531,12 @@ out:
531 return NULL; 531 return NULL;
532} 532}
533 533
534static unsigned short swap_entry_free(struct swap_info_struct *p, 534static unsigned char swap_entry_free(struct swap_info_struct *p,
535 swp_entry_t entry, unsigned short usage) 535 swp_entry_t entry, unsigned char usage)
536{ 536{
537 unsigned long offset = swp_offset(entry); 537 unsigned long offset = swp_offset(entry);
538 unsigned short count; 538 unsigned char count;
539 unsigned short has_cache; 539 unsigned char has_cache;
540 540
541 count = p->swap_map[offset]; 541 count = p->swap_map[offset];
542 has_cache = count & SWAP_HAS_CACHE; 542 has_cache = count & SWAP_HAS_CACHE;
@@ -591,7 +591,7 @@ void swap_free(swp_entry_t entry)
591void swapcache_free(swp_entry_t entry, struct page *page) 591void swapcache_free(swp_entry_t entry, struct page *page)
592{ 592{
593 struct swap_info_struct *p; 593 struct swap_info_struct *p;
594 unsigned short count; 594 unsigned char count;
595 595
596 p = swap_info_get(entry); 596 p = swap_info_get(entry);
597 if (p) { 597 if (p) {
@@ -975,7 +975,7 @@ static unsigned int find_next_to_unuse(struct swap_info_struct *si,
975{ 975{
976 unsigned int max = si->max; 976 unsigned int max = si->max;
977 unsigned int i = prev; 977 unsigned int i = prev;
978 int count; 978 unsigned char count;
979 979
980 /* 980 /*
981 * No need for swap_lock here: we're just looking 981 * No need for swap_lock here: we're just looking
@@ -1013,8 +1013,8 @@ static int try_to_unuse(unsigned int type)
1013{ 1013{
1014 struct swap_info_struct *si = swap_info[type]; 1014 struct swap_info_struct *si = swap_info[type];
1015 struct mm_struct *start_mm; 1015 struct mm_struct *start_mm;
1016 unsigned short *swap_map; 1016 unsigned char *swap_map;
1017 unsigned short swcount; 1017 unsigned char swcount;
1018 struct page *page; 1018 struct page *page;
1019 swp_entry_t entry; 1019 swp_entry_t entry;
1020 unsigned int i = 0; 1020 unsigned int i = 0;
@@ -1174,6 +1174,12 @@ static int try_to_unuse(unsigned int type)
1174 * If that's wrong, then we should worry more about 1174 * If that's wrong, then we should worry more about
1175 * exit_mmap() and do_munmap() cases described above: 1175 * exit_mmap() and do_munmap() cases described above:
1176 * we might be resetting SWAP_MAP_MAX too early here. 1176 * we might be resetting SWAP_MAP_MAX too early here.
1177 *
1178 * Yes, that's wrong: though very unlikely, swap count 0x7ffe
1179 * could surely occur if pid_max raised from PID_MAX_DEFAULT;
1180 * and we are now lowering SWAP_MAP_MAX to 0x7e, making it
1181 * much easier to reach. But the next patch will fix that.
1182 *
1177 * We know "Undead"s can happen, they're okay, so don't 1183 * We know "Undead"s can happen, they're okay, so don't
1178 * report them; but do report if we reset SWAP_MAP_MAX. 1184 * report them; but do report if we reset SWAP_MAP_MAX.
1179 */ 1185 */
@@ -1492,7 +1498,7 @@ bad_bmap:
1492SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 1498SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
1493{ 1499{
1494 struct swap_info_struct *p = NULL; 1500 struct swap_info_struct *p = NULL;
1495 unsigned short *swap_map; 1501 unsigned char *swap_map;
1496 struct file *swap_file, *victim; 1502 struct file *swap_file, *victim;
1497 struct address_space *mapping; 1503 struct address_space *mapping;
1498 struct inode *inode; 1504 struct inode *inode;
@@ -1762,7 +1768,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
1762 sector_t span; 1768 sector_t span;
1763 unsigned long maxpages = 1; 1769 unsigned long maxpages = 1;
1764 unsigned long swapfilepages; 1770 unsigned long swapfilepages;
1765 unsigned short *swap_map = NULL; 1771 unsigned char *swap_map = NULL;
1766 struct page *page = NULL; 1772 struct page *page = NULL;
1767 struct inode *inode = NULL; 1773 struct inode *inode = NULL;
1768 int did_down = 0; 1774 int did_down = 0;
@@ -1938,13 +1944,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
1938 goto bad_swap; 1944 goto bad_swap;
1939 1945
1940 /* OK, set up the swap map and apply the bad block list */ 1946 /* OK, set up the swap map and apply the bad block list */
1941 swap_map = vmalloc(maxpages * sizeof(short)); 1947 swap_map = vmalloc(maxpages);
1942 if (!swap_map) { 1948 if (!swap_map) {
1943 error = -ENOMEM; 1949 error = -ENOMEM;
1944 goto bad_swap; 1950 goto bad_swap;
1945 } 1951 }
1946 1952
1947 memset(swap_map, 0, maxpages * sizeof(short)); 1953 memset(swap_map, 0, maxpages);
1948 for (i = 0; i < swap_header->info.nr_badpages; i++) { 1954 for (i = 0; i < swap_header->info.nr_badpages; i++) {
1949 int page_nr = swap_header->info.badpages[i]; 1955 int page_nr = swap_header->info.badpages[i];
1950 if (page_nr <= 0 || page_nr >= swap_header->info.last_page) { 1956 if (page_nr <= 0 || page_nr >= swap_header->info.last_page) {
@@ -2082,12 +2088,12 @@ void si_swapinfo(struct sysinfo *val)
2082 * - swap-cache reference is requested but there is already one. -> EEXIST 2088 * - swap-cache reference is requested but there is already one. -> EEXIST
2083 * - swap-cache reference is requested but the entry is not used. -> ENOENT 2089 * - swap-cache reference is requested but the entry is not used. -> ENOENT
2084 */ 2090 */
2085static int __swap_duplicate(swp_entry_t entry, unsigned short usage) 2091static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
2086{ 2092{
2087 struct swap_info_struct *p; 2093 struct swap_info_struct *p;
2088 unsigned long offset, type; 2094 unsigned long offset, type;
2089 unsigned short count; 2095 unsigned char count;
2090 unsigned short has_cache; 2096 unsigned char has_cache;
2091 int err = -EINVAL; 2097 int err = -EINVAL;
2092 2098
2093 if (non_swap_entry(entry)) 2099 if (non_swap_entry(entry))