[PATCH] ZVC: Support NR_SLAB_RECLAIMABLE / NR_SLAB_UNRECLAIMABLE

Remove the atomic counter for slab_reclaim_pages and replace the counter
and NR_SLAB with two ZVC counter that account for unreclaimable and
reclaimable slab pages: NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE.

Change the check in vmscan.c to refer to to NR_SLAB_RECLAIMABLE.  The
intend seems to be to check for slab pages that could be freed.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

7 files changed, 18 insertions, 22 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 8507ee9cd573..eea8eefd51a8 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -116,7 +116,7 @@ int __vm_enough_memory(long pages, int cap_sys_admin)
                  * which are reclaimable, under pressure.  The dentry
                  * cache and most inode caches should fall into this
                  */
-                free += atomic_read(&slab_reclaim_pages);
+                free += global_page_state(NR_SLAB_RECLAIMABLE);
 
                 /*
                  * Leave the last 3% for root
diff --git a/mm/nommu.c b/mm/nommu.c
index c576df71e3bb..d99dea31e443 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1133,7 +1133,7 @@ int __vm_enough_memory(long pages, int cap_sys_admin)
                  * which are reclaimable, under pressure.  The dentry
                  * cache and most inode caches should fall into this
                  */
-                free += atomic_read(&slab_reclaim_pages);
+                free += global_page_state(NR_SLAB_RECLAIMABLE);
 
                 /*
                  * Leave the last 3% for root
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5da6bc4e0a6b..47e98423b30d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1304,7 +1304,8 @@ void show_free_areas(void)
                 global_page_state(NR_WRITEBACK),
                 global_page_state(NR_UNSTABLE_NFS),
                 nr_free_pages(),
-                global_page_state(NR_SLAB),
+                global_page_state(NR_SLAB_RECLAIMABLE) +
+                        global_page_state(NR_SLAB_UNRECLAIMABLE),
                 global_page_state(NR_FILE_MAPPED),
                 global_page_state(NR_PAGETABLE));
 
diff --git a/mm/slab.c b/mm/slab.c
index 13b5050f84cc..7a48eb1a60c8 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -736,14 +736,6 @@ static DEFINE_MUTEX(cache_chain_mutex);
 static struct list_head cache_chain;
 
 /*
- * vm_enough_memory() looks at this to determine how many slab-allocated pages
- * are possibly freeable under pressure
- *
- * SLAB_RECLAIM_ACCOUNT turns this on per-slab
- */
-atomic_t slab_reclaim_pages;
-
-/*
  * chicken and egg problem: delay the per-cpu array allocation
  * until the general caches are up.
  */
@@ -1580,8 +1572,11 @@ static void *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 
         nr_pages = (1 << cachep->gfporder);
         if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
-                atomic_add(nr_pages, &slab_reclaim_pages);
-        add_zone_page_state(page_zone(page), NR_SLAB, nr_pages);
+                add_zone_page_state(page_zone(page),
+                        NR_SLAB_RECLAIMABLE, nr_pages);
+        else
+                add_zone_page_state(page_zone(page),
+                        NR_SLAB_UNRECLAIMABLE, nr_pages);
         for (i = 0; i < nr_pages; i++)
                 __SetPageSlab(page + i);
         return page_address(page);
@@ -1596,7 +1591,12 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
         struct page *page = virt_to_page(addr);
         const unsigned long nr_freed = i;
 
-        sub_zone_page_state(page_zone(page), NR_SLAB, nr_freed);
+        if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
+                sub_zone_page_state(page_zone(page),
+                                NR_SLAB_RECLAIMABLE, nr_freed);
+        else
+                sub_zone_page_state(page_zone(page),
+                                NR_SLAB_UNRECLAIMABLE, nr_freed);
         while (i--) {
                 BUG_ON(!PageSlab(page));
                 __ClearPageSlab(page);
@@ -1605,8 +1605,6 @@ static void kmem_freepages(struct kmem_cache *cachep, void *addr)
         if (current->reclaim_state)
                 current->reclaim_state->reclaimed_slab += nr_freed;
         free_pages((unsigned long)addr, cachep->gfporder);
-        if (cachep->flags & SLAB_RECLAIM_ACCOUNT)
-                atomic_sub(1 << cachep->gfporder, &slab_reclaim_pages);
 }
 
 static void kmem_rcu_free(struct rcu_head *head)
diff --git a/mm/slob.c b/mm/slob.c
index 4c28a421b270..20188627347c 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -339,7 +339,3 @@ void kmem_cache_init(void)
 
         mod_timer(&slob_timer, jiffies + HZ);
 }
-
-atomic_t slab_reclaim_pages = ATOMIC_INIT(0);
-EXPORT_SYMBOL(slab_reclaim_pages);
-
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5154c25e8440..349797ba4bac 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1378,7 +1378,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
         for_each_zone(zone)
                 lru_pages += zone->nr_active + zone->nr_inactive;
 
-        nr_slab = global_page_state(NR_SLAB);
+        nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
         /* If slab caches are huge, it's better to hit them first */
         while (nr_slab >= lru_pages) {
                 reclaim_state.reclaimed_slab = 0;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 968c0072e19a..490d8c1a0ded 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -458,7 +458,8 @@ static char *vmstat_text[] = {
         "nr_anon_pages",
         "nr_mapped",
         "nr_file_pages",
-        "nr_slab",
+        "nr_slab_reclaimable",
+        "nr_slab_unreclaimable",
         "nr_page_table_pages",
         "nr_dirty",
         "nr_writeback",