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rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()

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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 <sasha.levin@oracle.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Looks-good-to: Christoph Lameter <cl@linux.com>
This commit is contained in:
Paul E. McKenney 2014-06-19 14:57:10 -07:00
commit 546a9d8519
2 changed files with 12 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

10
include/linux/rcupdate.h
View file

@ -358,9 +358,19 @@ void wait_rcu_gp(call_rcu_func_t crf);
* initialization. * initialization.
*/ */
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD #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 init_rcu_head_on_stack(struct rcu_head *head);
void destroy_rcu_head_on_stack(struct rcu_head *head); void destroy_rcu_head_on_stack(struct rcu_head *head);
#else /* !CONFIG_DEBUG_OBJECTS_RCU_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) static inline void init_rcu_head_on_stack(struct rcu_head *head)
{ {
} }

4
kernel/rcu/update.c
View file

@ -200,12 +200,12 @@ void wait_rcu_gp(call_rcu_func_t crf)
EXPORT_SYMBOL_GPL(wait_rcu_gp); EXPORT_SYMBOL_GPL(wait_rcu_gp);
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD #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); 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); debug_object_free(head, &rcuhead_debug_descr);
} }