I was able to reproduce the issue on my side on Ubuntu 7.0.0-22.22:
```
$ uname -a
Linux special10 7.0.0-22-generic #22-Ubuntu SMP PREEMPT Mon May 25 14:44:32 UTC
2026 s390x GNU/Linux
$ time make -j$(nproc) all
...
real 6m28.256s
user 139m0.780s
sys 148m59.040s
$ sudo perf top
53.25% [kernel] [k] _raw_spin_lock_irqsave
3.45% [kernel] [k] folios_put_refs
1.28% [kernel] [k] arch_spin_relax
0.94% [kernel] [k] folio_batch_move_lru
0.83% [kernel] [k] post_alloc_hook.localalias
```
The issue is also reproducible in upstream stable/linux-7.0.y:
```
$ uname -a
Linux special10 7.0.11 #3 SMP PREEMPT Tue Jun 2 16:45:39 UTC 2026 s390x
GNU/Linux
$ time make -j$(nproc) all
...
real 6m7.652s
user 134m25.548s
sys 132m36.549s
$ sudo perf top
51.48% [kernel] [k] _raw_spin_lock_irqsave
3.35% [kernel] [k] folios_put_refs
1.39% [kernel] [k] arch_spin_relax
0.98% [kernel] [k] folio_batch_move_lru
0.88% [kernel] [k] post_alloc_hook
```
The issue is not reproducible in amd64.
** Changed in: linux (Ubuntu)
Assignee: Skipper Bug Screeners (skipper-screen-team) => Massimiliano
Pellizzer (mpellizzer)
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https://bugs.launchpad.net/bugs/2154748
Title:
[Ubuntu 26.04] Severe Performance Degradation on kernel 7.0.0-15
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