[Devel] [PATCH RHEL7 COMMIT] ms/mm: slub: SLUB_DEBUG=n: use the same alloc/free hooks as for SLUB_DEBUG=y

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.6
------>
commit e79a1d458f45de9a672aefd76753949780b6af16
Author: Andrey Ryabinin <aryabinin at odin.com>
Date:   Thu Sep 3 19:27:34 2015 +0400

    ms/mm: slub: SLUB_DEBUG=n: use the same alloc/free hooks as for SLUB_DEBUG=y
    
    https://jira.sw.ru/browse/PSBM-26429
    
    From: Andrey Ryabinin <a.ryabinin at samsung.com>
    
    commit 02e72cc61713185013d958baba508288ba2a0157 upstream.
    
    There are two versions of alloc/free hooks now - one for
    CONFIG_SLUB_DEBUG=y and another one for CONFIG_SLUB_DEBUG=n.
    
    I see no reason why calls to other debugging subsystems (LOCKDEP,
    DEBUG_ATOMIC_SLEEP, KMEMCHECK and FAILSLAB) are hidden under SLUB_DEBUG.
    All this features should work regardless of SLUB_DEBUG config, as all of
    them already have own Kconfig options.
    
    This also fixes failslab for CONFIG_SLUB_DEBUG=n configuration.  It
    simply has not worked before because should_failslab() call was in a
    hook hidden under "#ifdef CONFIG_SLUB_DEBUG #else".
    
    Note: There is one concealed change in allocation path for SLUB_DEBUG=n
    and all other debugging features disabled.  The might_sleep_if() call
    can generate some code even if DEBUG_ATOMIC_SLEEP=n.  For
    PREEMPT_VOLUNTARY=y might_sleep() inserts _cond_resched() call, but I
    think it should be ok.
    
    Signed-off-by: Andrey Ryabinin <a.ryabinin at samsung.com>
    Cc: Christoph Lameter <cl at linux.com>
    Cc: Pekka Enberg <penberg at kernel.org>
    Cc: David Rientjes <rientjes at google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    Signed-off-by: Andrey Ryabinin <aryabinin at odin.com>
    
    Signed-off-by: Andrey Ryabinin <aryabinin at odin.com>
---
 mm/slub.c | 90 ++++++++++++++++++++++++++++-----------------------------------
 1 file changed, 40 insertions(+), 50 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 51772b6..f39e69c 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -928,50 +928,6 @@ static void trace(struct kmem_cache *s, struct page *page, void *object,
 }
 
 /*
- * Hooks for other subsystems that check memory allocations. In a typical
- * production configuration these hooks all should produce no code at all.
- */
-static inline int slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags)
-{
-	flags &= gfp_allowed_mask;
-	lockdep_trace_alloc(flags);
-	might_sleep_if(flags & __GFP_WAIT);
-	WARN_ON((flags & __GFP_FS) && current->journal_info);
-
-	return should_failslab(s->object_size, flags, s->flags);
-}
-
-static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags, void *object)
-{
-	flags &= gfp_allowed_mask;
-	kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
-	kmemleak_alloc_recursive(object, s->object_size, 1, s->flags, flags);
-}
-
-static inline void slab_free_hook(struct kmem_cache *s, void *x)
-{
-	kmemleak_free_recursive(x, s->flags);
-
-	/*
-	 * Trouble is that we may no longer disable interupts in the fast path
-	 * So in order to make the debug calls that expect irqs to be
-	 * disabled we need to disable interrupts temporarily.
-	 */
-#if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP)
-	{
-		unsigned long flags;
-
-		local_irq_save(flags);
-		kmemcheck_slab_free(s, x, s->object_size);
-		debug_check_no_locks_freed(x, s->object_size);
-		local_irq_restore(flags);
-	}
-#endif
-	if (!(s->flags & SLAB_DEBUG_OBJECTS))
-		debug_check_no_obj_freed(x, s->object_size);
-}
-
-/*
  * Tracking of fully allocated slabs for debugging purposes.
  *
  * list_lock must be held.
@@ -1256,16 +1212,50 @@ static inline void inc_slabs_node(struct kmem_cache *s, int node,
 							int objects) {}
 static inline void dec_slabs_node(struct kmem_cache *s, int node,
 							int objects) {}
-
+#endif /* CONFIG_SLUB_DEBUG */
+/*
+ * Hooks for other subsystems that check memory allocations. In a typical
+ * production configuration these hooks all should produce no code at all.
+ */
 static inline int slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags)
-							{ return 0; }
+{
+	flags &= gfp_allowed_mask;
+	lockdep_trace_alloc(flags);
+	might_sleep_if(flags & __GFP_WAIT);
+	WARN_ON((flags & __GFP_FS) && current->journal_info);
 
-static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
-		void *object) {}
+	return should_failslab(s->object_size, flags, s->flags);
+}
 
-static inline void slab_free_hook(struct kmem_cache *s, void *x) {}
+static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags, void *object)
+{
+	flags &= gfp_allowed_mask;
+	kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
+	kmemleak_alloc_recursive(object, s->object_size, 1, s->flags, flags);
+}
 
-#endif /* CONFIG_SLUB_DEBUG */
+static inline void slab_free_hook(struct kmem_cache *s, void *x)
+{
+	kmemleak_free_recursive(x, s->flags);
+
+	/*
+	 * Trouble is that we may no longer disable interupts in the fast path
+	 * So in order to make the debug calls that expect irqs to be
+	 * disabled we need to disable interrupts temporarily.
+	 */
+#if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP)
+	{
+		unsigned long flags;
+
+		local_irq_save(flags);
+		kmemcheck_slab_free(s, x, s->object_size);
+		debug_check_no_locks_freed(x, s->object_size);
+		local_irq_restore(flags);
+	}
+#endif
+	if (!(s->flags & SLAB_DEBUG_OBJECTS))
+		debug_check_no_obj_freed(x, s->object_size);
+}
 
 /*
  * Slab allocation and freeing