Paul, Neeraj, and Stable Team: I've run into a case with rcu_tasks_postscan where the warning introduced as part of 46aa886c4("rcu-tasks: Fix IPI failure handling in trc_wait_for_one_reader") is getting triggered when trc_wait_for_one_reader sends an IPI to a CPU that is offline. This is occurring on a platform that has hotplug slots available but not populated. I don't believe the bug is caused by this change, but I do think that Paul's commit that confines the postscan operation to just the active CPUs would help prevent this from happening.
Would the RCU maintainers be amenable to having this patch backported to the 5.10 and 5.15 branches as well? I've attached cherry-picks of the relevant commits to minimize the additional work needed.
Thanks,
-K
Paul E. McKenney (1): rcu-tasks: Idle tasks on offline CPUs are in quiescent states
kernel/rcu/tasks.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)