From 243e19ba4b4485cf6e5718bd121fed40875f6f8e Mon Sep 17 00:00:00 2001
From: Christoph Lameter <clameter@sgi.com>
Date: Thu, 9 Aug 2007 07:51:54 -0700
Subject: SLUB: Add debugging for slab defrag

Add some debugging printks for slab defragmentation

Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
 mm/slub.c   |   16 ++++++++++++++--
 mm/vmscan.c |    2 ++
 2 files changed, 16 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2007-11-06 22:25:51.155978887 -0800
+++ linux-2.6/mm/slub.c	2007-11-06 22:26:02.157479525 -0800
@@ -2543,8 +2543,10 @@ int kmem_cache_isolate_slab(struct page 
 	 * This is necessary to make sure that the page does not vanish
 	 * from under us before we are able to check the result.
 	 */
-	if (!get_page_unless_zero(page))
+	if (!get_page_unless_zero(page)) {
+		printk(KERN_INFO "isolate %p zero ref\n", page);
 		return rc;
+	}
 
 	local_irq_save(flags);
 	state = slab_lock(page);
@@ -2555,6 +2557,8 @@ int kmem_cache_isolate_slab(struct page 
 	if (!reclaimable_slab(flags) || !page->inuse) {
 		slab_unlock(page, state);
 		put_page(page);
+		printk(KERN_INFO "isolate faillock %p flags=%lx %s\n",
+			page, page->flags, PageSlab(page)?page->slab->name:"--");
 		goto out;
 	}
 
@@ -2581,6 +2585,7 @@ int kmem_cache_isolate_slab(struct page 
 		remove_full(s, page);
 	slab_unlock(page, state | FROZEN);
 	rc = 0;
+	printk(KERN_INFO "Isolated %s slab=%p objects=%d\n", s->name, page, page->inuse);
 out:
 	local_irq_restore(flags);
 	return rc;
@@ -2847,6 +2852,7 @@ int kmem_cache_reclaim(struct list_head 
 	void **scratch;
 	struct page *page;
 	struct page *page2;
+	int pages = 0;
 
 	if (list_empty(zaplist))
 		return 0;
@@ -2857,10 +2863,12 @@ int kmem_cache_reclaim(struct list_head 
 
 	list_for_each_entry_safe(page, page2, zaplist, lru) {
 		list_del(&page->lru);
+		pages++;
 		if (kmem_cache_vacate(page, scratch) == 0)
 				freed++;
 	}
 	kfree(scratch);
+	printk("recovered %d of %d slabs.\n", freed, pages);
 	return freed;
 }
 
@@ -2915,8 +2923,11 @@ static unsigned long __kmem_cache_shrink
 
 	spin_unlock_irqrestore(&n->list_lock, flags);
 
-	if (s->kick)
+	if (s->kick) {
+		if (!list_empty(&zaplist))
+			printk(KERN_INFO "Reclaiming %s:", s->name);
 		freed += kmem_cache_reclaim(&zaplist);
+	}
 	return freed;
 }
 
@@ -2954,6 +2965,7 @@ static unsigned long __kmem_cache_defrag
 	 * then no defragmentation is necessary.
 	 */
 	ratio = (objects_in_full_slabs + count_partial(n)) * 100 / capacity;
+	printk(KERN_INFO "defrag: %s ratio=%ld defrag_ratio=%d\n", s->name, ratio, s->defrag_ratio);
 	if (ratio > s->defrag_ratio)
 		return 0;
 
Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c	2007-11-06 21:33:31.689680393 -0800
+++ linux-2.6/mm/vmscan.c	2007-11-06 22:26:02.169478690 -0800
@@ -832,6 +832,8 @@ static unsigned long shrink_inactive_lis
 						-(nr_taken - nr_active));
 		zone->pages_scanned += nr_scan;
 		spin_unlock_irq(&zone->lru_lock);
+		if (!list_empty(&slab_list))
+			printk(KERN_INFO "Shrink_inactive_list:");
 		kmem_cache_reclaim(&slab_list);
 
 		nr_scanned += nr_scan;