[RFC v2 30/34] mm: slub: Make object_map_lock a raw_spinlock_t

From: Vlastimil Babka
Date: Wed Jun 09 2021 - 07:41:16 EST


From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

The variable object_map is protected by object_map_lock. The lock is always
acquired in debug code and within already atomic context

Make object_map_lock a raw_spinlock_t.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
---
mm/slub.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 6e747e0d7dcd..cfd5a7660375 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -432,7 +432,7 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,

#ifdef CONFIG_SLUB_DEBUG
static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
-static DEFINE_SPINLOCK(object_map_lock);
+static DEFINE_RAW_SPINLOCK(object_map_lock);

static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
struct page *page)
@@ -457,7 +457,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page)
{
VM_BUG_ON(!irqs_disabled());

- spin_lock(&object_map_lock);
+ raw_spin_lock(&object_map_lock);

__fill_map(object_map, s, page);

@@ -467,7 +467,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page)
static void put_map(unsigned long *map) __releases(&object_map_lock)
{
VM_BUG_ON(map != object_map);
- spin_unlock(&object_map_lock);
+ raw_spin_unlock(&object_map_lock);
}

static inline unsigned int size_from_object(struct kmem_cache *s)
--
2.31.1