[PATCH] mm/slub, kunit: Make slub_kunit unaffected by global slub debugging flags

[Hyeonggon Yoo <42.hyeyoo@gmail.com>]

slub_kunit does not expect other debugging flags to be set when running
tests. When SLAB_RED_ZONE flag is set globally, test fails because the
flag affects number of errors reported.

To make slub_kunit unaffected by global slub debugging flags, introduce
SLAB_NO_GLOBAL_FLAGS to ignore them. It's still allowed to specify
debugging flags by specifying cache name(s) in slub_debug parameter.

Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
---
 include/linux/slab.h |  3 +++
 lib/slub_kunit.c     | 10 +++++-----
 mm/slab.h            |  5 +++--
 mm/slub.c            |  3 +++
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 0381868e5118..11fe2c28422d 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -112,6 +112,9 @@
 #define SLAB_KASAN		0
 #endif
 
+/* Ignore globally specified debugging flags */
+#define SLAB_NO_GLOBAL_FLAGS	((slab_flags_t __force)0x10000000U)
+
 /* The following flags affect the page allocator grouping pages by mobility */
 /* Objects are reclaimable */
 #define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0x00020000U)
diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c
index 8662dc6cb509..acf061dc558d 100644
--- a/lib/slub_kunit.c
+++ b/lib/slub_kunit.c
@@ -12,7 +12,7 @@ static int slab_errors;
 static void test_clobber_zone(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_alloc", 64, 0,
-				SLAB_RED_ZONE, NULL);
+				SLAB_RED_ZONE|SLAB_NO_GLOBAL_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kasan_disable_current();
@@ -30,7 +30,7 @@ static void test_clobber_zone(struct kunit *test)
 static void test_next_pointer(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_next_ptr_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_GLOBAL_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 	unsigned long tmp;
 	unsigned long *ptr_addr;
@@ -75,7 +75,7 @@ static void test_next_pointer(struct kunit *test)
 static void test_first_word(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_1th_word_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_GLOBAL_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kmem_cache_free(s, p);
@@ -90,7 +90,7 @@ static void test_first_word(struct kunit *test)
 static void test_clobber_50th_byte(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_50th_word_free", 64, 0,
-				SLAB_POISON, NULL);
+				SLAB_POISON|SLAB_NO_GLOBAL_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kmem_cache_free(s, p);
@@ -106,7 +106,7 @@ static void test_clobber_50th_byte(struct kunit *test)
 static void test_clobber_redzone_free(struct kunit *test)
 {
 	struct kmem_cache *s = kmem_cache_create("TestSlub_RZ_free", 64, 0,
-				SLAB_RED_ZONE, NULL);
+				SLAB_RED_ZONE|SLAB_NO_GLOBAL_FLAGS, NULL);
 	u8 *p = kmem_cache_alloc(s, GFP_KERNEL);
 
 	kasan_disable_current();
diff --git a/mm/slab.h b/mm/slab.h
index c7f2abc2b154..69946131208a 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -330,7 +330,7 @@ static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
 			  SLAB_ACCOUNT)
 #elif defined(CONFIG_SLUB)
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
-			  SLAB_TEMPORARY | SLAB_ACCOUNT)
+			  SLAB_TEMPORARY | SLAB_ACCOUNT | SLAB_NO_GLOBAL_FLAGS)
 #else
 #define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE)
 #endif
@@ -349,7 +349,8 @@ static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
 			      SLAB_NOLEAKTRACE | \
 			      SLAB_RECLAIM_ACCOUNT | \
 			      SLAB_TEMPORARY | \
-			      SLAB_ACCOUNT)
+			      SLAB_ACCOUNT | \
+			      SLAB_NO_GLOBAL_FLAGS)
 
 bool __kmem_cache_empty(struct kmem_cache *);
 int __kmem_cache_shutdown(struct kmem_cache *);
diff --git a/mm/slub.c b/mm/slub.c
index 71e8663f6037..2a3cffd7b27f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1592,6 +1592,9 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
 	if (flags & SLAB_NOLEAKTRACE)
 		slub_debug_local &= ~SLAB_STORE_USER;
 
+	if (flags & SLAB_NO_GLOBAL_FLAGS)
+		slub_debug_local = 0;
+
 	len = strlen(name);
 	next_block = slub_debug_string;
 	/* Go through all blocks of debug options, see if any matches our slab's name */
-- 
2.33.1