Public bug reported:
**Title:**
`rcu_tasks_wait_gp stalls on linux-image-7.0.0-28/29-generic (HWE noble), not
present on 6.17.0-40-generic`
**Description:**
System: Intel Core i7-8700K, Linux Mint 22.3 "Zena" (Ubuntu 24.04 noble
base), x86_64
Affected kernels: `7.0.0-28-generic` and `7.0.0-29-generic`
(linux-generic-hwe-24.04)
Working kernel: `6.17.0-40-generic` — zero occurrences of the same issue
**Symptom:**
Repeated `rcu_tasks_wait_gp` grace-period warnings in the kernel log shortly
after boot, occurring continuously during normal desktop use (not idle).
**Reproduction / measurements:**
- On `7.0.0-28-generic`: ~656 occurrences of `rcu_tasks_wait_gp` logged over
roughly 6 hours of normal desktop use (`journalctl -k`)
- On `7.0.0-29-generic`: 19 occurrences within the first 10 minutes after boot
(~114/hour), rising to worse than the -28 rate
- On `6.17.0-40-generic`: 0 occurrences over multiple days of equivalent use,
including with identical workload (LocalWP/Electron app running MySQL +
Node/GraphQL services)
**Correlated symptom:**
While on the affected kernels, an Electron-based local dev app (LocalWP)
exhibited unexpected MySQL service restarts (multiple `mysqld` startups within
a couple of minutes, on changing ports) that did not occur on
`6.17.0-40-generic` under the same usage pattern. This may or may not be
directly caused by the RCU stalls but was consistently reproducible alongside
them.
**To reproduce:**
1. Boot into `7.0.0-28-generic` or `7.0.0-29-generic`
2. Run: `journalctl -k -b 0 --no-pager | grep -c "rcu_tasks_wait_gp"` after 10+
minutes of normal use
3. Compare against the same check on `6.17.0-40-generic` after equivalent uptime
**System info:**
```
Linux z-390 6.17.0-40-generic #40~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Jun 23
16:48:12 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
Distributor ID: Linuxmint
Description: Linux Mint 22.3
Release: 22.3
Codename: zena
CPU: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
```
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "lspci-vnvn.log"
https://bugs.launchpad.net/bugs/2164624/+attachment/5993814/+files/lspci-vnvn.log
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https://bugs.launchpad.net/bugs/2164624
Title:
rcu_tasks_wait_gp stalls on 7.0.0-28/29-generic (HWE noble), absent on
6.17.0-40-generic
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