slub: convert SLAB_DEBUG_FREE to SLAB_CONSISTENCY_CHECKS

SLAB_DEBUG_FREE allows expensive consistency checks at free to be turned
on or off.  Expand its use to be able to turn off all consistency
checks.  This gives a nice speed up if you only want features such as
poisoning or tracing.

Credit to Mathias Krause for the original work which inspired this
series

Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/vm/slub.txt b/Documentation/vm/slub.txt
index f0d3409..8465241 100644 (file)
--- a/Documentation/vm/slub.txt
+++ b/Documentation/vm/slub.txt
@@ -35,8 +35,8 @@ slub_debug=<Debug-Options>,<slab name>
                                Enable options only for select slabs
 
 Possible debug options are
-       F               Sanity checks on (enables SLAB_DEBUG_FREE. Sorry
-                       SLAB legacy issues)
+       F               Sanity checks on (enables SLAB_DEBUG_CONSISTENCY_CHECKS
+                       Sorry SLAB legacy issues)
        Z               Red zoning
        P               Poisoning (object and padding)
        U               User tracking (free and alloc)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 5d49f0c..e4b5687 100644 (file)
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -20,7 +20,7 @@
  * Flags to pass to kmem_cache_create().
  * The ones marked DEBUG are only valid if CONFIG_DEBUG_SLAB is set.
  */
-#define SLAB_DEBUG_FREE                0x00000100UL    /* DEBUG: Perform (expensive) checks on free */
+#define SLAB_CONSISTENCY_CHECKS        0x00000100UL    /* DEBUG: Perform (expensive) checks on alloc/free */
 #define SLAB_RED_ZONE          0x00000400UL    /* DEBUG: Red zone objs in a cache */
 #define SLAB_POISON            0x00000800UL    /* DEBUG: Poison objects */
 #define SLAB_HWCACHE_ALIGN     0x00002000UL    /* Align objs on cache lines */

diff --git a/mm/slab.h b/mm/slab.h
index e880bbe..b793436 100644 (file)
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -125,7 +125,7 @@ static inline unsigned long kmem_cache_flags(unsigned long object_size,
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
 #elif defined(CONFIG_SLUB_DEBUG)
 #define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
-                         SLAB_TRACE | SLAB_DEBUG_FREE)
+                         SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
 #else
 #define SLAB_DEBUG_FLAGS (0)
 #endif
@@ -311,7 +311,8 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
         * to not do even the assignment. In that case, slab_equal_or_root
         * will also be a constant.
         */
-       if (!memcg_kmem_enabled() && !unlikely(s->flags & SLAB_DEBUG_FREE))
+       if (!memcg_kmem_enabled() &&
+           !unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
                return s;
 
        page = virt_to_head_page(x);

diff --git a/mm/slub.c b/mm/slub.c
index 744d29b..9cde663 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -160,7 +160,7 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
  */
 #define MAX_PARTIAL 10
 
-#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
+#define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
                                SLAB_POISON | SLAB_STORE_USER)
 
 /*
@@ -1007,20 +1007,32 @@ static void setup_object_debug(struct kmem_cache *s, struct page *page,
        init_tracking(s, object);
 }
 
-static noinline int alloc_debug_processing(struct kmem_cache *s,
+static inline int alloc_consistency_checks(struct kmem_cache *s,
                                        struct page *page,
                                        void *object, unsigned long addr)
 {
        if (!check_slab(s, page))
-               goto bad;
+               return 0;
 
        if (!check_valid_pointer(s, page, object)) {
                object_err(s, page, object, "Freelist Pointer check fails");
-               goto bad;
+               return 0;
        }
 
        if (!check_object(s, page, object, SLUB_RED_INACTIVE))
-               goto bad;
+               return 0;
+
+       return 1;
+}
+
+static noinline int alloc_debug_processing(struct kmem_cache *s,
+                                       struct page *page,
+                                       void *object, unsigned long addr)
+{
+       if (s->flags & SLAB_CONSISTENCY_CHECKS) {
+               if (!alloc_consistency_checks(s, page, object, addr))
+                       goto bad;
+       }
 
        /* Success perform special debug activities for allocs */
        if (s->flags & SLAB_STORE_USER)
@@ -1043,39 +1055,21 @@ bad:
        return 0;
 }
 
-/* Supports checking bulk free of a constructed freelist */
-static noinline int free_debug_processing(
-       struct kmem_cache *s, struct page *page,
-       void *head, void *tail, int bulk_cnt,
-       unsigned long addr)
+static inline int free_consistency_checks(struct kmem_cache *s,
+               struct page *page, void *object, unsigned long addr)
 {
-       struct kmem_cache_node *n = get_node(s, page_to_nid(page));
-       void *object = head;
-       int cnt = 0;
-       unsigned long uninitialized_var(flags);
-       int ret = 0;
-
-       spin_lock_irqsave(&n->list_lock, flags);
-       slab_lock(page);
-
-       if (!check_slab(s, page))
-               goto out;
-
-next_object:
-       cnt++;
-
        if (!check_valid_pointer(s, page, object)) {
                slab_err(s, page, "Invalid object pointer 0x%p", object);
-               goto out;
+               return 0;
        }
 
        if (on_freelist(s, page, object)) {
                object_err(s, page, object, "Object already free");
-               goto out;
+               return 0;
        }
 
        if (!check_object(s, page, object, SLUB_RED_ACTIVE))
-               goto out;
+               return 0;
 
        if (unlikely(s != page->slab_cache)) {
                if (!PageSlab(page)) {
@@ -1088,7 +1082,37 @@ next_object:
                } else
                        object_err(s, page, object,
                                        "page slab pointer corrupt.");
-               goto out;
+               return 0;
+       }
+       return 1;
+}
+
+/* Supports checking bulk free of a constructed freelist */
+static noinline int free_debug_processing(
+       struct kmem_cache *s, struct page *page,
+       void *head, void *tail, int bulk_cnt,
+       unsigned long addr)
+{
+       struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+       void *object = head;
+       int cnt = 0;
+       unsigned long uninitialized_var(flags);
+       int ret = 0;
+
+       spin_lock_irqsave(&n->list_lock, flags);
+       slab_lock(page);
+
+       if (s->flags & SLAB_CONSISTENCY_CHECKS) {
+               if (!check_slab(s, page))
+                       goto out;
+       }
+
+next_object:
+       cnt++;
+
+       if (s->flags & SLAB_CONSISTENCY_CHECKS) {
+               if (!free_consistency_checks(s, page, object, addr))
+                       goto out;
        }
 
        if (s->flags & SLAB_STORE_USER)
@@ -1145,7 +1169,7 @@ static int __init setup_slub_debug(char *str)
        for (; *str && *str != ','; str++) {
                switch (tolower(*str)) {
                case 'f':
-                       slub_debug |= SLAB_DEBUG_FREE;
+                       slub_debug |= SLAB_CONSISTENCY_CHECKS;
                        break;
                case 'z':
                        slub_debug |= SLAB_RED_ZONE;
@@ -1449,7 +1473,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
        int order = compound_order(page);
        int pages = 1 << order;
 
-       if (kmem_cache_debug(s)) {
+       if (s->flags & SLAB_CONSISTENCY_CHECKS) {
                void *p;
 
                slab_pad_check(s, page);
@@ -4769,16 +4793,16 @@ SLAB_ATTR_RO(total_objects);
 
 static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
 {
-       return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
+       return sprintf(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
 }
 
 static ssize_t sanity_checks_store(struct kmem_cache *s,
                                const char *buf, size_t length)
 {
-       s->flags &= ~SLAB_DEBUG_FREE;
+       s->flags &= ~SLAB_CONSISTENCY_CHECKS;
        if (buf[0] == '1') {
                s->flags &= ~__CMPXCHG_DOUBLE;
-               s->flags |= SLAB_DEBUG_FREE;
+               s->flags |= SLAB_CONSISTENCY_CHECKS;
        }
        return length;
 }
@@ -5313,7 +5337,7 @@ static char *create_unique_id(struct kmem_cache *s)
                *p++ = 'd';
        if (s->flags & SLAB_RECLAIM_ACCOUNT)
                *p++ = 'a';
-       if (s->flags & SLAB_DEBUG_FREE)
+       if (s->flags & SLAB_CONSISTENCY_CHECKS)
                *p++ = 'F';
        if (!(s->flags & SLAB_NOTRACK))
                *p++ = 't';

diff --git a/tools/vm/slabinfo.c b/tools/vm/slabinfo.c
index 86e698d..1889163 100644 (file)
--- a/tools/vm/slabinfo.c
+++ b/tools/vm/slabinfo.c
@@ -135,7 +135,7 @@ static void usage(void)
                "\nValid debug options (FZPUT may be combined)\n"
                "a / A          Switch on all debug options (=FZUP)\n"
                "-              Switch off all debug options\n"
-               "f / F          Sanity Checks (SLAB_DEBUG_FREE)\n"
+               "f / F          Sanity Checks (SLAB_CONSISTENCY_CHECKS)\n"
                "z / Z          Redzoning\n"
                "p / P          Poisoning\n"
                "u / U          Tracking\n"