5 files changed, 85 insertions, 25 deletions

diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt
index bb1f5c6e28b..510917ff59e 100644
--- a/Documentation/vm/slub.txt
+++ b/Documentation/vm/slub.txt
@@ -41,6 +41,8 @@ Possible debug options are
         P               Poisoning (object and padding)
         U               User tracking (free and alloc)
         T               Trace (please only use on single slabs)
+        O               Switch debugging off for caches that would have
+                        caused higher minimum slab orders
         -               Switch all debugging off (useful if the kernel is
                         configured with CONFIG_SLUB_DEBUG_ON)
 
@@ -59,6 +61,14 @@ to the dentry cache with
 
         slub_debug=F,dentry
 
+Debugging options may require the minimum possible slab order to increase as
+a result of storing the metadata (for example, caches with PAGE_SIZE object
+sizes).  This has a higher liklihood of resulting in slab allocation errors
+in low memory situations or if there's high fragmentation of memory.  To
+switch off debugging for such caches by default, use
+
+        slub_debug=O
+
 In case you forgot to enable debugging on the kernel command line: It is
 possible to enable debugging manually when the kernel is up. Look at the
 contents of:
diff --git a/include/linux/slob_def.h b/include/linux/slob_def.h
index bb5368df4be..0ec00b39d00 100644
--- a/include/linux/slob_def.h
+++ b/include/linux/slob_def.h
@@ -34,9 +34,4 @@ static __always_inline void *__kmalloc(size_t size, gfp_t flags)
         return kmalloc(size, flags);
 }
 
-static inline void kmem_cache_init_late(void)
-{
-        /* Nothing to do */
-}
-
 #endif /* __LINUX_SLOB_DEF_H */
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index c1c862b1d01..5ad70a60fd7 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -153,12 +153,10 @@ static __always_inline int kmalloc_index(size_t size)
         if (size <= KMALLOC_MIN_SIZE)
                 return KMALLOC_SHIFT_LOW;
 
-#if KMALLOC_MIN_SIZE <= 64
-        if (size > 64 && size <= 96)
+        if (KMALLOC_MIN_SIZE <= 32 && size > 64 && size <= 96)
                 return 1;
-        if (size > 128 && size <= 192)
+        if (KMALLOC_MIN_SIZE <= 64 && size > 128 && size <= 192)
                 return 2;
-#endif
         if (size <=          8) return 3;
         if (size <=         16) return 4;
         if (size <=         32) return 5;
@@ -304,6 +302,4 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 }
 #endif
 
-void __init kmem_cache_init_late(void);
-
 #endif /* _LINUX_SLUB_DEF_H */
diff --git a/mm/slob.c b/mm/slob.c
index 9641da3d5e5..837ebd64cc3 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -692,3 +692,8 @@ void __init kmem_cache_init(void)
 {
         slob_ready = 1;
 }
+
+void __init kmem_cache_init_late(void)
+{
+        /* Nothing to do */
+}
diff --git a/mm/slub.c b/mm/slub.c
index b6276753626..417ed843b25 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -141,6 +141,13 @@
                                 SLAB_POISON | SLAB_STORE_USER)
 
 /*
+ * Debugging flags that require metadata to be stored in the slab.  These get
+ * disabled when slub_debug=O is used and a cache's min order increases with
+ * metadata.
+ */
+#define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
+
+/*
  * Set of flags that will prevent slab merging
  */
 #define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
@@ -325,6 +332,7 @@ static int slub_debug;
 #endif
 
 static char *slub_debug_slabs;
+static int disable_higher_order_debug;
 
 /*
  * Object debugging
@@ -646,7 +654,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
         slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
         print_section("Padding", end - remainder, remainder);
 
-        restore_bytes(s, "slab padding", POISON_INUSE, start, end);
+        restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
         return 0;
 }
 
@@ -976,6 +984,15 @@ static int __init setup_slub_debug(char *str)
                  */
                 goto check_slabs;
 
+        if (tolower(*str) == 'o') {
+                /*
+                 * Avoid enabling debugging on caches if its minimum order
+                 * would increase as a result.
+                 */
+                disable_higher_order_debug = 1;
+                goto out;
+        }
+
         slub_debug = 0;
         if (*str == '-')
                 /*
@@ -1026,8 +1043,8 @@ static unsigned long kmem_cache_flags(unsigned long objsize,
          * Enable debugging if selected on the kernel commandline.
          */
         if (slub_debug && (!slub_debug_slabs ||
-            strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)) == 0))
-                        flags |= slub_debug;
+                !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))
+                flags |= slub_debug;
 
         return flags;
 }
@@ -1109,8 +1126,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
         }
 
         if (kmemcheck_enabled
-                && !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS)))
-        {
+                && !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
                 int pages = 1 << oo_order(oo);
 
                 kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);
@@ -1560,6 +1576,10 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
                 "default order: %d, min order: %d\n", s->name, s->objsize,
                 s->size, oo_order(s->oo), oo_order(s->min));
 
+        if (oo_order(s->min) > get_order(s->objsize))
+                printk(KERN_WARNING "  %s debugging increased min order, use "
+                       "slub_debug=O to disable.\n", s->name);
+
         for_each_online_node(node) {
                 struct kmem_cache_node *n = get_node(s, node);
                 unsigned long nr_slabs;
@@ -2001,7 +2021,7 @@ static inline int calculate_order(int size)
                                 return order;
                         fraction /= 2;
                 }
-                min_objects --;
+                min_objects--;
         }
 
         /*
@@ -2400,6 +2420,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
          * on bootup.
          */
         align = calculate_alignment(flags, align, s->objsize);
+        s->align = align;
 
         /*
          * SLUB stores one object immediately after another beginning from
@@ -2452,6 +2473,18 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
 
         if (!calculate_sizes(s, -1))
                 goto error;
+        if (disable_higher_order_debug) {
+                /*
+                 * Disable debugging flags that store metadata if the min slab
+                 * order increased.
+                 */
+                if (get_order(s->size) > get_order(s->objsize)) {
+                        s->flags &= ~DEBUG_METADATA_FLAGS;
+                        s->offset = 0;
+                        if (!calculate_sizes(s, -1))
+                                goto error;
+                }
+        }
 
         /*
          * The larger the object size is, the more pages we want on the partial
@@ -2790,6 +2823,11 @@ static s8 size_index[24] = {
         2       /* 192 */
 };
 
+static inline int size_index_elem(size_t bytes)
+{
+        return (bytes - 1) / 8;
+}
+
 static struct kmem_cache *get_slab(size_t size, gfp_t flags)
 {
         int index;
@@ -2798,7 +2836,7 @@ static struct kmem_cache *get_slab(size_t size, gfp_t flags)
                 if (!size)
                         return ZERO_SIZE_PTR;
 
-                index = size_index[(size - 1) / 8];
+                index = size_index[size_index_elem(size)];
         } else
                 index = fls(size - 1);
 
@@ -3156,10 +3194,12 @@ void __init kmem_cache_init(void)
         slab_state = PARTIAL;
 
         /* Caches that are not of the two-to-the-power-of size */
-        if (KMALLOC_MIN_SIZE <= 64) {
+        if (KMALLOC_MIN_SIZE <= 32) {
                 create_kmalloc_cache(&kmalloc_caches[1],
                                 "kmalloc-96", 96, GFP_NOWAIT);
                 caches++;
+        }
+        if (KMALLOC_MIN_SIZE <= 64) {
                 create_kmalloc_cache(&kmalloc_caches[2],
                                 "kmalloc-192", 192, GFP_NOWAIT);
                 caches++;
@@ -3186,17 +3226,28 @@ void __init kmem_cache_init(void)
         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
                 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 
-        for (i = 8; i < KMALLOC_MIN_SIZE; i += 8)
-                size_index[(i - 1) / 8] = KMALLOC_SHIFT_LOW;
+        for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
+                int elem = size_index_elem(i);
+                if (elem >= ARRAY_SIZE(size_index))
+                        break;
+                size_index[elem] = KMALLOC_SHIFT_LOW;
+        }
 
-        if (KMALLOC_MIN_SIZE == 128) {
+        if (KMALLOC_MIN_SIZE == 64) {
+                /*
+                 * The 96 byte size cache is not used if the alignment
+                 * is 64 byte.
+                 */
+                for (i = 64 + 8; i <= 96; i += 8)
+                        size_index[size_index_elem(i)] = 7;
+        } else if (KMALLOC_MIN_SIZE == 128) {
                 /*
                  * The 192 byte sized cache is not used if the alignment
                  * is 128 byte. Redirect kmalloc to use the 256 byte cache
                  * instead.
                  */
                 for (i = 128 + 8; i <= 192; i += 8)
-                        size_index[(i - 1) / 8] = 8;
+                        size_index[size_index_elem(i)] = 8;
         }
 
         slab_state = UP;
@@ -4543,8 +4594,11 @@ static int sysfs_slab_add(struct kmem_cache *s)
         }
 
         err = sysfs_create_group(&s->kobj, &slab_attr_group);
-        if (err)
+        if (err) {
+                kobject_del(&s->kobj);
+                kobject_put(&s->kobj);
                 return err;
+        }
         kobject_uevent(&s->kobj, KOBJ_ADD);
         if (!unmergeable) {
                 /* Setup first alias */
@@ -4726,7 +4780,7 @@ static const struct file_operations proc_slabinfo_operations = {
 
 static int __init slab_proc_init(void)
 {
-        proc_create("slabinfo",S_IWUSR|S_IRUGO,NULL,&proc_slabinfo_operations);
+        proc_create("slabinfo", S_IRUGO, NULL, &proc_slabinfo_operations);
         return 0;
 }
 module_init(slab_proc_init);