Re: [BUG] RCU stall / hung rcu_gp: process_srcu blocked in synchronize_rcu_normal triggered by perf trace teardown on 7.0.0-rc1

[Sasha Levin]

On Mon, Mar 02, 2026 at 11:25:45AM -0500, Steven Rostedt wrote:

On Mon,  2 Mar 2026 08:36:13 -0500
Sasha Levin <sas...@kernel.org> wrote:

This response was AI-generated by bug-bot. The analysis may contain errors — 
please verify independently.

## Bug Summary

This is an RCU stall and hung task deadlock on 7.0.0-rc1, triggered by perf trace 
teardown under perf interrupt storm conditions. The perf subsystem's tracepoint 
unregistration path now blocks on SRCU (tracepoint_srcu), which in turn blocks on 
RCU grace period completion, creating a cascading stall when RCU progress is 
delayed by perf NMI interrupt storms. Severity: system hang (multiple tasks 
blocked >143s, eventual complete stall).

Hmm, this analysis corresponds nicely to what I was thinking when looking
at the stack dumps, but it gives a bit more details than I would have.

Thanks for the feedback!

I'll finish fine-tuning this script, and publish it in a day or two :)

--
Thanks,
Sasha