In message: [linux-yocto][v6.12/standard/preempt-rt/base][PATCH 0/3]
intel-x86-64: fix the call trace in acpi s4
on 03/02/2026 Jianpeng Chang wrote:
> Hi Bruce,
>
> Could you please merge these three patches into
> v6.12/standard/preempt-rt/base?
Does 6.18-rt need the same changes ?
Bruce
>
> Allowing irq_work to be scheduled while trying to suspend has shown
> to cause problems as some architectures interpret the pending
> interrupts as a reason to not suspend. This became a problem for
> printk() with the introduction of NBCON consoles.
>
> Linux yocto introduce nbcon since commit 3b739d55b861 ("serial: 8250: Switch
> to nbcon console") in 6.12 preempt-rt.
> This will encounter call trace when suspend in acpi s4 occasionally:
> unchecked MSR access error: WRMSR to 0x83f (tried to write
> 0x00000000000000f6) at rIP: 0xffffffff8947e2f6
> (native_apic_msr_write+0x26/0x50)
> Call Trace:
> <TASK>
> ? x2apic_send_IPI_self+0x19/0x20
> arch_irq_work_raise+0x28/0x40
> __irq_work_queue_local+0x40/0xf0
> irq_work_queue+0x31/0x60
> nbcon_kthreads_wake+0x5f/0x80
> vprintk_emit+0x2c9/0x440
> vprintk_deferred+0x21/0x30
> vprintk+0x12/0x20
> _printk+0x6c/0x87
> swsusp_save+0x26/0x3a3
> swsusp_arch_suspend+0x63/0x70
> hibernation_snapshot+0x349/0x550
> hibernate.cold+0xba/0x2a7
>
> There is no nbcon in upstream v6.12, these patches will not go into v6.12.
> So backport them to avoid calling irq_work when suspend to fix unchecked MSR
> access error.
>
> Patch 3 is a fix for the former one.
> See the links:
> https://lore.kernel.org/all/[email protected]/
> https://lore.kernel.org/all/[email protected]/
>
> Regards,
> Jianpeng
>
> John Ogness (3):
> printk: Allow printk_trigger_flush() to flush all types
> printk: Avoid scheduling irq_work on suspend
> printk: Avoid irq_work for printk_deferred() on suspend
>
> kernel/printk/internal.h | 8 ++--
> kernel/printk/nbcon.c | 9 ++++-
> kernel/printk/printk.c | 83 ++++++++++++++++++++++++++++++++--------
> 3 files changed, 79 insertions(+), 21 deletions(-)
>
> --
> 2.49.1
>
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