Currently, free_debug_processing has a comment "Keep node_lock to preserve integrity until the object is actually freed". In actuallity, the lock is dropped immediately in __slab_free. Rather than wait until __slab_free and potentially throw off the unlikely marking, just drop the lock in __slab_free. This also lets free_debug_processing take its own copy of the spinlock flags rather than trying to share the ones from __slab_free. Since there is no use for the node afterwards, change the return type of free_debug_processing to return an int like alloc_debug_processing.
Credit to Mathias Krause for the original work which inspired this series Signed-off-by: Laura Abbott <[email protected]> --- I didn't add Christoph's ack from the last time due to some rebasing. --- mm/slub.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 2e1355a..2d5a774 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1068,16 +1068,17 @@ bad: } /* Supports checking bulk free of a constructed freelist */ -static noinline struct kmem_cache_node *free_debug_processing( +static noinline int free_debug_processing( struct kmem_cache *s, struct page *page, void *head, void *tail, int bulk_cnt, - unsigned long addr, unsigned long *flags) + unsigned long addr) { struct kmem_cache_node *n = get_node(s, page_to_nid(page)); void *object = head; int cnt = 0; + unsigned long uninitialized_var(flags); - spin_lock_irqsave(&n->list_lock, *flags); + spin_lock_irqsave(&n->list_lock, flags); slab_lock(page); if (!check_slab(s, page)) @@ -1130,17 +1131,14 @@ out: bulk_cnt, cnt); slab_unlock(page); - /* - * Keep node_lock to preserve integrity - * until the object is actually freed - */ - return n; + spin_unlock_irqrestore(&n->list_lock, flags); + return 1; fail: slab_unlock(page); - spin_unlock_irqrestore(&n->list_lock, *flags); + spin_unlock_irqrestore(&n->list_lock, flags); slab_fix(s, "Object at 0x%p not freed", object); - return NULL; + return 0; } static int __init setup_slub_debug(char *str) @@ -1231,7 +1229,7 @@ static inline void setup_object_debug(struct kmem_cache *s, static inline int alloc_debug_processing(struct kmem_cache *s, struct page *page, void *object, unsigned long addr) { return 0; } -static inline struct kmem_cache_node *free_debug_processing( +static inline int free_debug_processing( struct kmem_cache *s, struct page *page, void *head, void *tail, int bulk_cnt, unsigned long addr, unsigned long *flags) { return NULL; } @@ -2648,8 +2646,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page, stat(s, FREE_SLOWPATH); if (kmem_cache_debug(s) && - !(n = free_debug_processing(s, page, head, tail, cnt, - addr, &flags))) + !free_debug_processing(s, page, head, tail, cnt, addr)) return; do { -- 2.5.0
