From 546a9d8519ed137b2804a3f5a3659003039dd49c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 19 Jun 2014 14:57:10 -0700 Subject: [PATCH] rcu: Export debug_init_rcu_head() and and debug_init_rcu_head() Currently, call_rcu() relies on implicit allocation and initialization for the debug-objects handling of RCU callbacks. If you hammer the kernel hard enough with Sasha's modified version of trinity, you can end up with the sl*b allocators recursing into themselves via this implicit call_rcu() allocation. This commit therefore exports the debug_init_rcu_head() and debug_rcu_head_free() functions, which permits the allocators to allocated and pre-initialize the debug-objects information, so that there no longer any need for call_rcu() to do that initialization, which in turn prevents the recursion into the memory allocators. Reported-by: Sasha Levin Suggested-by: Thomas Gleixner Signed-off-by: Paul E. McKenney Acked-by: Thomas Gleixner Looks-good-to: Christoph Lameter --- include/linux/rcupdate.h | 10 ++++++++++ kernel/rcu/update.c | 4 ++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 5a75d19aa661..13bbfbde41b9 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -358,9 +358,19 @@ void wait_rcu_gp(call_rcu_func_t crf); * initialization. */ #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD +void init_rcu_head(struct rcu_head *head); +void destroy_rcu_head(struct rcu_head *head); void init_rcu_head_on_stack(struct rcu_head *head); void destroy_rcu_head_on_stack(struct rcu_head *head); #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ +static inline void init_rcu_head(struct rcu_head *head) +{ +} + +static inline void destroy_rcu_head(struct rcu_head *head) +{ +} + static inline void init_rcu_head_on_stack(struct rcu_head *head) { } diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index a2aeb4df0f60..0fb691e63ce6 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -200,12 +200,12 @@ void wait_rcu_gp(call_rcu_func_t crf) EXPORT_SYMBOL_GPL(wait_rcu_gp); #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD -static inline void debug_init_rcu_head(struct rcu_head *head) +void init_rcu_head(struct rcu_head *head) { debug_object_init(head, &rcuhead_debug_descr); } -static inline void debug_rcu_head_free(struct rcu_head *head) +void destroy_rcu_head(struct rcu_head *head) { debug_object_free(head, &rcuhead_debug_descr); } -- 2.34.1