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authorXuewen Yan <xuewen.yan@unisoc.com>2024-01-10 11:27:24 +0800
committerTejun Heo <tj@kernel.org>2024-01-16 10:20:44 -1000
commit1a65a6d17cbc58e1aeffb2be962acce49efbef9c (patch)
tree881459ba7fd95e359a4ef34397439d570a3c74b0
parent85f0ab43f9de62a4b9c1b503b07f1c33e5a6d2ab (diff)
workqueue: Add rcu lock check at the end of work item execution
Currently the workqueue just checks the atomic and locking states after work execution ends. However, sometimes, a work item may not unlock rcu after acquiring rcu_read_lock(). And as a result, it would cause rcu stall, but the rcu stall warning can not dump the work func, because the work has finished. In order to quickly discover those works that do not call rcu_read_unlock() after rcu_read_lock(), add the rcu lock check. Use rcu_preempt_depth() to check the work's rcu status. Normally, this value is 0. If this value is bigger than 0, it means the work are still holding rcu lock. If so, print err info and the work func. tj: Reworded the description for clarity. Minor formatting tweak. Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com> Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com> Reviewed-by: Waiman Long <longman@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
-rw-r--r--kernel/workqueue.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index ed442cefea7c..aec3efbaaf93 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2640,11 +2640,12 @@ __acquires(&pool->lock)
lock_map_release(&lockdep_map);
lock_map_release(&pwq->wq->lockdep_map);
- if (unlikely(in_atomic() || lockdep_depth(current) > 0)) {
- pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
+ if (unlikely(in_atomic() || lockdep_depth(current) > 0 ||
+ rcu_preempt_depth() > 0)) {
+ pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d/%d\n"
" last function: %ps\n",
- current->comm, preempt_count(), task_pid_nr(current),
- worker->current_func);
+ current->comm, preempt_count(), rcu_preempt_depth(),
+ task_pid_nr(current), worker->current_func);
debug_show_held_locks(current);
dump_stack();
}