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>
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5249749..c0d7b9e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -53,7 +53,7 @@
static DEFINE_MUTEX(swapon_mutex);
-static inline int swap_count(unsigned short ent)
+static inline unsigned char swap_count(unsigned char ent)
{
return ent & ~SWAP_HAS_CACHE;
}
@@ -203,7 +203,7 @@
#define LATENCY_LIMIT 256
static inline unsigned long scan_swap_map(struct swap_info_struct *si,
- unsigned short usage)
+ unsigned char usage)
{
unsigned long offset;
unsigned long scan_base;
@@ -531,12 +531,12 @@
return NULL;
}
-static unsigned short swap_entry_free(struct swap_info_struct *p,
- swp_entry_t entry, unsigned short usage)
+static unsigned char swap_entry_free(struct swap_info_struct *p,
+ swp_entry_t entry, unsigned char usage)
{
unsigned long offset = swp_offset(entry);
- unsigned short count;
- unsigned short has_cache;
+ unsigned char count;
+ unsigned char has_cache;
count = p->swap_map[offset];
has_cache = count & SWAP_HAS_CACHE;
@@ -591,7 +591,7 @@
void swapcache_free(swp_entry_t entry, struct page *page)
{
struct swap_info_struct *p;
- unsigned short count;
+ unsigned char count;
p = swap_info_get(entry);
if (p) {
@@ -975,7 +975,7 @@
{
unsigned int max = si->max;
unsigned int i = prev;
- int count;
+ unsigned char count;
/*
* No need for swap_lock here: we're just looking
@@ -1013,8 +1013,8 @@
{
struct swap_info_struct *si = swap_info[type];
struct mm_struct *start_mm;
- unsigned short *swap_map;
- unsigned short swcount;
+ unsigned char *swap_map;
+ unsigned char swcount;
struct page *page;
swp_entry_t entry;
unsigned int i = 0;
@@ -1174,6 +1174,12 @@
* If that's wrong, then we should worry more about
* exit_mmap() and do_munmap() cases described above:
* we might be resetting SWAP_MAP_MAX too early here.
+ *
+ * Yes, that's wrong: though very unlikely, swap count 0x7ffe
+ * could surely occur if pid_max raised from PID_MAX_DEFAULT;
+ * and we are now lowering SWAP_MAP_MAX to 0x7e, making it
+ * much easier to reach. But the next patch will fix that.
+ *
* We know "Undead"s can happen, they're okay, so don't
* report them; but do report if we reset SWAP_MAP_MAX.
*/
@@ -1492,7 +1498,7 @@
SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
{
struct swap_info_struct *p = NULL;
- unsigned short *swap_map;
+ unsigned char *swap_map;
struct file *swap_file, *victim;
struct address_space *mapping;
struct inode *inode;
@@ -1762,7 +1768,7 @@
sector_t span;
unsigned long maxpages = 1;
unsigned long swapfilepages;
- unsigned short *swap_map = NULL;
+ unsigned char *swap_map = NULL;
struct page *page = NULL;
struct inode *inode = NULL;
int did_down = 0;
@@ -1938,13 +1944,13 @@
goto bad_swap;
/* OK, set up the swap map and apply the bad block list */
- swap_map = vmalloc(maxpages * sizeof(short));
+ swap_map = vmalloc(maxpages);
if (!swap_map) {
error = -ENOMEM;
goto bad_swap;
}
- memset(swap_map, 0, maxpages * sizeof(short));
+ memset(swap_map, 0, maxpages);
for (i = 0; i < swap_header->info.nr_badpages; i++) {
int page_nr = swap_header->info.badpages[i];
if (page_nr <= 0 || page_nr >= swap_header->info.last_page) {
@@ -2082,12 +2088,12 @@
* - swap-cache reference is requested but there is already one. -> EEXIST
* - swap-cache reference is requested but the entry is not used. -> ENOENT
*/
-static int __swap_duplicate(swp_entry_t entry, unsigned short usage)
+static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
{
struct swap_info_struct *p;
unsigned long offset, type;
- unsigned short count;
- unsigned short has_cache;
+ unsigned char count;
+ unsigned char has_cache;
int err = -EINVAL;
if (non_swap_entry(entry))