On 3/17/22 09:10, Hyeonggon Yoo wrote:
> 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.
Given how we support globbing, I think it would be safest to just ignore
everything that comes from slub_debug parameter when the
SLAB_NO_GLOBAL_FLAGS flag is specified, even if it involves a (partial)
cache name match.
Maybe name it SLAB_NO_USER_FLAGS then?
> Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
> Signed-off-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
> ---
> 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 */
I'd add that this is intended for caches created for self-tests so they
always have flags as specified in the code.
> +#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 */
