9 files changed, 104 insertions, 8 deletions

diff --git a/arch/i386/kernel/syscall_table.S b/arch/i386/kernel/syscall_table.S
index 6cd1ed311f0..d408afaf649 100644
--- a/arch/i386/kernel/syscall_table.S
+++ b/arch/i386/kernel/syscall_table.S
@@ -251,7 +251,7 @@ ENTRY(sys_call_table)
         .long sys_io_submit
         .long sys_io_cancel
         .long sys_fadvise64     /* 250 */
-        .long sys_ni_syscall
+        .long sys_set_zone_reclaim
         .long sys_exit_group
         .long sys_lookup_dcookie
         .long sys_epoll_create
diff --git a/arch/ia64/kernel/entry.S b/arch/ia64/kernel/entry.S
index d99316c9be2..b1d5d3d5276 100644
--- a/arch/ia64/kernel/entry.S
+++ b/arch/ia64/kernel/entry.S
@@ -1579,7 +1579,7 @@ sys_call_table:
         data8 sys_keyctl
         data8 sys_ni_syscall
         data8 sys_ni_syscall                    // 1275
-        data8 sys_ni_syscall
+        data8 sys_set_zone_reclaim
         data8 sys_ni_syscall
         data8 sys_ni_syscall
         data8 sys_ni_syscall
diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h
index 61bcc1b1e3f..176413fb9ae 100644
--- a/include/asm-i386/unistd.h
+++ b/include/asm-i386/unistd.h
@@ -256,7 +256,7 @@
 #define __NR_io_submit          248
 #define __NR_io_cancel          249
 #define __NR_fadvise64          250
-
+#define __NR_set_zone_reclaim   251
 #define __NR_exit_group         252
 #define __NR_lookup_dcookie     253
 #define __NR_epoll_create       254
diff --git a/include/asm-ia64/unistd.h b/include/asm-ia64/unistd.h
index 33e26c557c5..f7f43ec2483 100644
--- a/include/asm-ia64/unistd.h
+++ b/include/asm-ia64/unistd.h
@@ -263,6 +263,7 @@
 #define __NR_add_key                    1271
 #define __NR_request_key                1272
 #define __NR_keyctl                     1273
+#define __NR_set_zone_reclaim           1276
 
 #ifdef __KERNEL__
 
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index beacd931b60..dfc2452ccb1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -145,6 +145,12 @@ struct zone {
         int                     all_unreclaimable; /* All pages pinned */
 
         /*
+         * Does the allocator try to reclaim pages from the zone as soon
+         * as it fails a watermark_ok() in __alloc_pages?
+         */
+        int                     reclaim_pages;
+
+        /*
          * prev_priority holds the scanning priority for this zone.  It is
          * defined as the scanning priority at which we achieved our reclaim
          * target at the previous try_to_free_pages() or balance_pgdat()
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 3bbc41be9bd..0d21e682d99 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -173,6 +173,7 @@ extern void swap_setup(void);
 
 /* linux/mm/vmscan.c */
 extern int try_to_free_pages(struct zone **, unsigned int, unsigned int);
+extern int zone_reclaim(struct zone *, unsigned int, unsigned int);
 extern int shrink_all_memory(int);
 extern int vm_swappiness;
 
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 0dda70ed1f9..6f15bea7d1a 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -77,6 +77,7 @@ cond_syscall(sys_request_key);
 cond_syscall(sys_keyctl);
 cond_syscall(compat_sys_keyctl);
 cond_syscall(compat_sys_socketcall);
+cond_syscall(sys_set_zone_reclaim);
 
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 40169f0b7e9..3c0f69ded6b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -724,6 +724,14 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
         return 1;
 }
 
+static inline int
+should_reclaim_zone(struct zone *z, unsigned int gfp_mask)
+{
+        if (!z->reclaim_pages)
+                return 0;
+        return 1;
+}
+
 /*
  * This is the 'heart' of the zoned buddy allocator.
  */
@@ -760,17 +768,32 @@ __alloc_pages(unsigned int __nocast gfp_mask, unsigned int order,
 
         classzone_idx = zone_idx(zones[0]);
 
- restart:
+restart:
         /* Go through the zonelist once, looking for a zone with enough free */
         for (i = 0; (z = zones[i]) != NULL; i++) {
-
-                if (!zone_watermark_ok(z, order, z->pages_low,
-                                       classzone_idx, 0, 0))
-                        continue;
+                int do_reclaim = should_reclaim_zone(z, gfp_mask);
 
                 if (!cpuset_zone_allowed(z))
                         continue;
 
+                /*
+                 * If the zone is to attempt early page reclaim then this loop
+                 * will try to reclaim pages and check the watermark a second
+                 * time before giving up and falling back to the next zone.
+                 */
+zone_reclaim_retry:
+                if (!zone_watermark_ok(z, order, z->pages_low,
+                                       classzone_idx, 0, 0)) {
+                        if (!do_reclaim)
+                                continue;
+                        else {
+                                zone_reclaim(z, gfp_mask, order);
+                                /* Only try reclaim once */
+                                do_reclaim = 0;
+                                goto zone_reclaim_retry;
+                        }
+                }
+
                 page = buffered_rmqueue(z, order, gfp_mask);
                 if (page)
                         goto got_pg;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6379ddbffd9..7da846960d8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1323,3 +1323,67 @@ static int __init kswapd_init(void)
 }
 
 module_init(kswapd_init)
+
+
+/*
+ * Try to free up some pages from this zone through reclaim.
+ */
+int zone_reclaim(struct zone *zone, unsigned int gfp_mask, unsigned int order)
+{
+        struct scan_control sc;
+        int nr_pages = 1 << order;
+        int total_reclaimed = 0;
+
+        /* The reclaim may sleep, so don't do it if sleep isn't allowed */
+        if (!(gfp_mask & __GFP_WAIT))
+                return 0;
+        if (zone->all_unreclaimable)
+                return 0;
+
+        sc.gfp_mask = gfp_mask;
+        sc.may_writepage = 0;
+        sc.may_swap = 0;
+        sc.nr_mapped = read_page_state(nr_mapped);
+        sc.nr_scanned = 0;
+        sc.nr_reclaimed = 0;
+        /* scan at the highest priority */
+        sc.priority = 0;
+
+        if (nr_pages > SWAP_CLUSTER_MAX)
+                sc.swap_cluster_max = nr_pages;
+        else
+                sc.swap_cluster_max = SWAP_CLUSTER_MAX;
+
+        shrink_zone(zone, &sc);
+        total_reclaimed = sc.nr_reclaimed;
+
+        return total_reclaimed;
+}
+
+asmlinkage long sys_set_zone_reclaim(unsigned int node, unsigned int zone,
+                                     unsigned int state)
+{
+        struct zone *z;
+        int i;
+
+        if (node >= MAX_NUMNODES || !node_online(node))
+                return -EINVAL;
+
+        /* This will break if we ever add more zones */
+        if (!(zone & (1<<ZONE_DMA|1<<ZONE_NORMAL|1<<ZONE_HIGHMEM)))
+                return -EINVAL;
+
+        for (i = 0; i < MAX_NR_ZONES; i++) {
+                if (!(zone & 1<<i))
+                        continue;
+
+                z = &NODE_DATA(node)->node_zones[i];
+
+                if (state)
+                        z->reclaim_pages = 1;
+                else
+                        z->reclaim_pages = 0;
+        }
+
+        return 0;
+}