On Fri, Aug 12, 2022 at 11:14:25AM +0200, Vlastimil Babka wrote:
> The only remaining user of object_map_lock is list_slab_objects().
> Obtaining the lock there used to happen under slab_lock() which implied
> disabling irqs on PREEMPT_RT, thus it's a raw_spinlock. With the
> slab_lock() removed, we can convert it to a normal spinlock.
>
> Also remove the get_map()/put_map() wrappers as list_slab_objects()
> became their only remaining user.
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> mm/slub.c | 36 ++++++------------------------------
> 1 file changed, 6 insertions(+), 30 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 32b79bc3ae6d..dffb5063acbf 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -565,7 +565,7 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
>
> #ifdef CONFIG_SLUB_DEBUG
> static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
> -static DEFINE_RAW_SPINLOCK(object_map_lock);
> +static DEFINE_SPINLOCK(object_map_lock);
>
> static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
> struct slab *slab)
> @@ -599,30 +599,6 @@ static bool slab_add_kunit_errors(void)
> static inline bool slab_add_kunit_errors(void) { return false; }
> #endif
>
> -/*
> - * Determine a map of objects in use in a slab.
> - *
> - * Node listlock must be held to guarantee that the slab does
> - * not vanish from under us.
> - */
> -static unsigned long *get_map(struct kmem_cache *s, struct slab *slab)
> - __acquires(&object_map_lock)
> -{
> - VM_BUG_ON(!irqs_disabled());
> -
> - raw_spin_lock(&object_map_lock);
> -
> - __fill_map(object_map, s, slab);
> -
> - return object_map;
> -}
> -
> -static void put_map(unsigned long *map) __releases(&object_map_lock)
> -{
> - VM_BUG_ON(map != object_map);
> - raw_spin_unlock(&object_map_lock);
> -}
> -
> static inline unsigned int size_from_object(struct kmem_cache *s)
> {
> if (s->flags & SLAB_RED_ZONE)
> @@ -4368,21 +4344,21 @@ static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
> {
> #ifdef CONFIG_SLUB_DEBUG
> void *addr = slab_address(slab);
> - unsigned long flags;
> - unsigned long *map;
> void *p;
>
> slab_err(s, slab, text, s->name);
>
> - map = get_map(s, slab);
> + spin_lock(&object_map_lock);
> + __fill_map(object_map, s, slab);
> +
> for_each_object(p, s, addr, slab->objects) {
>
> - if (!test_bit(__obj_to_index(s, addr, p), map)) {
> + if (!test_bit(__obj_to_index(s, addr, p), object_map)) {
> pr_err("Object 0x%p @offset=%tu\n", p, p - addr);
> print_tracking(s, p);
> }
> }
> - put_map(map);
> + spin_unlock(&object_map_lock);
> #endif
> }
>
> --
> 2.37.1
>
Looks good to me.
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
--
Thanks,
Hyeonggon
