[PATCH] vmscan: use unsigned longs

Turn basically everything in vmscan.c into `unsigned long'.  This is to avoid
the possibility that some piece of code in there might decide to operate upon
more than 4G (or even 2G) of pages in one hit.

This might be silly, but we'll need it one day.

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/mm.h

@@ -1046,7 +1046,7 @@ int in_gate_area_no_task(unsigned long addr);
 
 int drop_caches_sysctl_handler(struct ctl_table *, int, struct file *,
 					void __user *, size_t *, loff_t *);
-int shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
 			unsigned long lru_pages);
 void drop_pagecache(void);
 void drop_slab(void);

include/linux/swap.h

@@ -172,8 +172,8 @@ extern int rotate_reclaimable_page(struct page *page);
 extern void swap_setup(void);
 
 /* linux/mm/vmscan.c */
-extern int try_to_free_pages(struct zone **, gfp_t);
-extern int shrink_all_memory(int);
+extern unsigned long try_to_free_pages(struct zone **, gfp_t);
+extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
 
 #ifdef CONFIG_NUMA
@@ -190,11 +190,11 @@ static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 
 #ifdef CONFIG_MIGRATION
 extern int isolate_lru_page(struct page *p);
-extern int putback_lru_pages(struct list_head *l);
+extern unsigned long putback_lru_pages(struct list_head *l);
 extern int migrate_page(struct page *, struct page *);
 extern void migrate_page_copy(struct page *, struct page *);
 extern int migrate_page_remove_references(struct page *, struct page *, int);
-extern int migrate_pages(struct list_head *l, struct list_head *t,
+extern unsigned long migrate_pages(struct list_head *l, struct list_head *t,
 		struct list_head *moved, struct list_head *failed);
 extern int fail_migrate_page(struct page *, struct page *);
 #else

mm/vmscan.c

@@ -177,10 +177,11 @@ EXPORT_SYMBOL(remove_shrinker);
  *
  * Returns the number of slab objects which we shrunk.
  */
-int shrink_slab(unsigned long scanned, gfp_t gfp_mask, unsigned long lru_pages)
+unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
+			unsigned long lru_pages)
 {
 	struct shrinker *shrinker;
-	int ret = 0;
+	unsigned long ret = 0;
 
 	if (scanned == 0)
 		scanned = SWAP_CLUSTER_MAX;
@@ -410,12 +411,13 @@ cannot_free:
 /*
  * shrink_list adds the number of reclaimed pages to sc->nr_reclaimed
  */
-static int shrink_list(struct list_head *page_list, struct scan_control *sc)
+static unsigned long shrink_list(struct list_head *page_list,
+				struct scan_control *sc)
 {
 	LIST_HEAD(ret_pages);
 	struct pagevec freed_pvec;
 	int pgactivate = 0;
-	int reclaimed = 0;
+	unsigned long reclaimed = 0;
 
 	cond_resched();
 
@@ -599,11 +601,11 @@ static inline void move_to_lru(struct page *page)
  *
  * returns the number of pages put back.
  */
-int putback_lru_pages(struct list_head *l)
+unsigned long putback_lru_pages(struct list_head *l)
 {
 	struct page *page;
 	struct page *page2;
-	int count = 0;
+	unsigned long count = 0;
 
 	list_for_each_entry_safe(page, page2, l, lru) {
 		move_to_lru(page);
@@ -848,11 +850,11 @@ EXPORT_SYMBOL(migrate_page);
  *
  * Return: Number of pages not migrated when "to" ran empty.
  */
-int migrate_pages(struct list_head *from, struct list_head *to,
+unsigned long migrate_pages(struct list_head *from, struct list_head *to,
 		  struct list_head *moved, struct list_head *failed)
 {
-	int retry;
-	int nr_failed = 0;
+	unsigned long retry;
+	unsigned long nr_failed = 0;
 	int pass = 0;
 	struct page *page;
 	struct page *page2;
@@ -1069,12 +1071,13 @@ int isolate_lru_page(struct page *page)
  *
  * returns how many pages were moved onto *@dst.
  */
-static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
-			     struct list_head *dst, int *scanned)
+static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
+		struct list_head *src, struct list_head *dst,
+		unsigned long *scanned)
 {
-	int nr_taken = 0;
+	unsigned long nr_taken = 0;
 	struct page *page;
-	int scan = 0;
+	unsigned long scan = 0;
 
 	while (scan++ < nr_to_scan && !list_empty(src)) {
 		struct list_head *target;
@@ -1106,20 +1109,22 @@ static int isolate_lru_pages(int nr_to_scan, struct list_head *src,
 /*
  * shrink_cache() adds the number of pages reclaimed to sc->nr_reclaimed
  */
-static void shrink_cache(int max_scan, struct zone *zone, struct scan_control *sc)
+static void shrink_cache(unsigned long max_scan, struct zone *zone,
+			struct scan_control *sc)
 {
 	LIST_HEAD(page_list);
 	struct pagevec pvec;
+	unsigned long nr_scanned = 0;
 
 	pagevec_init(&pvec, 1);
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);
-	while (max_scan > 0) {
+	do {
 		struct page *page;
-		int nr_taken;
-		int nr_scan;
-		int nr_freed;
+		unsigned long nr_taken;
+		unsigned long nr_scan;
+		unsigned long nr_freed;
 
 		nr_taken = isolate_lru_pages(sc->swap_cluster_max,
 					     &zone->inactive_list,
@@ -1131,7 +1136,7 @@ static void shrink_cache(int max_scan, struct zone *zone, struct scan_control *s
 		if (nr_taken == 0)
 			goto done;
 
-		max_scan -= nr_scan;
+		nr_scanned += nr_scan;
 		nr_freed = shrink_list(&page_list, sc);
 
 		local_irq_disable();
@@ -1161,7 +1166,7 @@ static void shrink_cache(int max_scan, struct zone *zone, struct scan_control *s
 				spin_lock_irq(&zone->lru_lock);
 			}
 		}
-  	}
+  	} while (nr_scanned < max_scan);
 	spin_unlock_irq(&zone->lru_lock);
 done:
 	pagevec_release(&pvec);
@@ -1185,11 +1190,12 @@ done:
  * But we had to alter page->flags anyway.
  */
 static void
-refill_inactive_zone(int nr_pages, struct zone *zone, struct scan_control *sc)
+refill_inactive_zone(unsigned long nr_pages, struct zone *zone,
+			struct scan_control *sc)
 {
-	int pgmoved;
+	unsigned long pgmoved;
 	int pgdeactivate = 0;
-	int pgscanned;
+	unsigned long pgscanned;
 	LIST_HEAD(l_hold);	/* The pages which were snipped off */
 	LIST_HEAD(l_inactive);	/* Pages to go onto the inactive_list */
 	LIST_HEAD(l_active);	/* Pages to go onto the active_list */
@@ -1323,8 +1329,8 @@ refill_inactive_zone(int nr_pages, struct zone *zone, struct scan_control *sc)
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
-static void
-shrink_zone(int priority, struct zone *zone, struct scan_control *sc)
+static void shrink_zone(int priority, struct zone *zone,
+			struct scan_control *sc)
 {
 	unsigned long nr_active;
 	unsigned long nr_inactive;
@@ -1387,8 +1393,8 @@ shrink_zone(int priority, struct zone *zone, struct scan_control *sc)
  * If a zone is deemed to be full of pinned pages then just give it a light
  * scan then give up on it.
  */
-static void
-shrink_caches(int priority, struct zone **zones, struct scan_control *sc)
+static void shrink_caches(int priority, struct zone **zones,
+				struct scan_control *sc)
 {
 	int i;
 
@@ -1425,11 +1431,12 @@ shrink_caches(int priority, struct zone **zones, struct scan_control *sc)
  * holds filesystem locks which prevent writeout this might not work, and the
  * allocation attempt will fail.
  */
-int try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
+unsigned long try_to_free_pages(struct zone **zones, gfp_t gfp_mask)
 {
 	int priority;
 	int ret = 0;
-	int total_scanned = 0, total_reclaimed = 0;
+	unsigned long total_scanned = 0;
+	unsigned long total_reclaimed = 0;
 	struct reclaim_state *reclaim_state = current->reclaim_state;
 	unsigned long lru_pages = 0;
 	int i;
@@ -1525,13 +1532,15 @@ out:
  * the page allocator fallback scheme to ensure that aging of pages is balanced
  * across the zones.
  */
-static int balance_pgdat(pg_data_t *pgdat, int nr_pages, int order)
+static unsigned long balance_pgdat(pg_data_t *pgdat, unsigned long nr_pages,
+				int order)
 {
-	int to_free = nr_pages;
+	unsigned long to_free = nr_pages;
 	int all_zones_ok;
 	int priority;
 	int i;
-	int total_scanned, total_reclaimed;
+	unsigned long total_scanned;
+	unsigned long total_reclaimed;
 	struct reclaim_state *reclaim_state = current->reclaim_state;
 	struct scan_control sc = {
 		.gfp_mask = GFP_KERNEL,
@@ -1776,22 +1785,23 @@ void wakeup_kswapd(struct zone *zone, int order)
  * Try to free `nr_pages' of memory, system-wide.  Returns the number of freed
  * pages.
  */
-int shrink_all_memory(int nr_pages)
+unsigned long shrink_all_memory(unsigned long nr_pages)
 {
 	pg_data_t *pgdat;
-	int nr_to_free = nr_pages;
-	int ret = 0;
+	unsigned long nr_to_free = nr_pages;
+	unsigned long ret = 0;
 	struct reclaim_state reclaim_state = {
 		.reclaimed_slab = 0,
 	};
 
 	current->reclaim_state = &reclaim_state;
 	for_each_pgdat(pgdat) {
-		int freed;
+		unsigned long freed;
+
 		freed = balance_pgdat(pgdat, nr_to_free, 0);
 		ret += freed;
 		nr_to_free -= freed;
-		if (nr_to_free <= 0)
+		if ((long)nr_to_free <= 0)
 			break;
 	}
 	current->reclaim_state = NULL;
@@ -1805,8 +1815,7 @@ int shrink_all_memory(int nr_pages)
    away, we get changed to run anywhere: as the first one comes back,
    restore their cpu bindings. */
 static int __devinit cpu_callback(struct notifier_block *nfb,
-				  unsigned long action,
-				  void *hcpu)
+				  unsigned long action, void *hcpu)
 {
 	pg_data_t *pgdat;
 	cpumask_t mask;
@@ -1826,10 +1835,15 @@ static int __devinit cpu_callback(struct notifier_block *nfb,
 static int __init kswapd_init(void)
 {
 	pg_data_t *pgdat;
+
 	swap_setup();
-	for_each_pgdat(pgdat)
-		pgdat->kswapd
-		= find_task_by_pid(kernel_thread(kswapd, pgdat, CLONE_KERNEL));
+	for_each_pgdat(pgdat) {
+		pid_t pid;
+
+		pid = kernel_thread(kswapd, pgdat, CLONE_KERNEL);
+		BUG_ON(pid < 0);
+		pgdat->kswapd = find_task_by_pid(pid);
+	}
 	total_memory = nr_free_pagecache_pages();
 	hotcpu_notifier(cpu_callback, 0);
 	return 0;
@@ -1873,7 +1887,7 @@ int zone_reclaim_interval __read_mostly = 30*HZ;
  */
 static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 {
-	const int nr_pages = 1 << order;
+	const unsigned long nr_pages = 1 << order;
 	struct task_struct *p = current;
 	struct reclaim_state reclaim_state;
 	int priority;
@@ -1881,7 +1895,8 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 		.may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
 		.may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
 		.nr_mapped = read_page_state(nr_mapped),
-		.swap_cluster_max = max(nr_pages, SWAP_CLUSTER_MAX),
+		.swap_cluster_max = max_t(unsigned long, nr_pages,
+					SWAP_CLUSTER_MAX),
 		.gfp_mask = gfp_mask,
 	};
 
@@ -1966,4 +1981,3 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	return __zone_reclaim(zone, gfp_mask, order);
 }
 #endif
-