[GIT PULL] Urgent ACPI support fix for v6.18

[GIT PULL] Urgent ACPI support fix for v6.18

[Rafael J. Wysocki]

Hi Linus,

Please pull from the tag

 git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
 acpi-6.18-rc8

with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3

 Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"

on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d

 Linux 6.18-rc7

to receive an urgent ACPI support fix for 6.18.

This reverts a commit that attempted to make the code in the ACPI
processor driver more straightforward, but it turned out to cause
the kernel to crash on at least one system, along with some further
cleanups on top of it.

Thanks!


---------------

Rafael J. Wysocki (5):
      Revert "ACPI: processor: Do not expose global variable acpi_idle_driver"
      Revert "ACPI: processor: idle: Redefine two functions as void"
      Revert "ACPI: processor: idle: Rearrange declarations in header file"
      Revert "ACPI: processor: Remove unused empty stubs of some functions"
      Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"

---------------

 drivers/acpi/processor_driver.c |   6 +--
 drivers/acpi/processor_idle.c   | 115 ++++++++++++++++------------------------
 include/acpi/processor.h        |  34 +++++++++---
 3 files changed, 76 insertions(+), 79 deletions(-)

Re: [GIT PULL] Urgent ACPI support fix for v6.18

[pr-tracker-bot]

The pull request you sent on Wed, 26 Nov 2025 13:54:24 +0100:

> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git acpi-6.18-rc8

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/a10d15a08f62bf97c707ef3c2a7493604c1bcc89

Thank you!

-- 
Deet-doot-dot, I am a bot.
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Re: [GIT PULL] Urgent ACPI support fix for v6.18

[lihuisong (C)]

Hello Rafael,

在 2025/11/26 20:54, Rafael J. Wysocki 写道:
> Hi Linus,
>
> Please pull from the tag
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>   acpi-6.18-rc8
>
> with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3
>
>   Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"
>
> on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
>
>   Linux 6.18-rc7
>
> to receive an urgent ACPI support fix for 6.18.
>
> This reverts a commit that attempted to make the code in the ACPI
> processor driver more straightforward, but it turned out to cause
> the kernel to crash on at least one system, along with some further
> cleanups on top of it.
I just found that "ACPI: processor: idle: Optimize ACPI idle driver 
registration" depends on the change
about cpuhp_setup_state in the commit [1]. Or many CPUs don't create 
cpuidle directory.
What is the crash? Do you have releated trace?

[1] 
https://lore.kernel.org/all/20240529133446.28446-2-Jonathan.Cameron@huawei.com/ 

>
>
> ---------------
>
> Rafael J. Wysocki (5):
>        Revert "ACPI: processor: Do not expose global variable acpi_idle_driver"
>        Revert "ACPI: processor: idle: Redefine two functions as void"
>        Revert "ACPI: processor: idle: Rearrange declarations in header file"
>        Revert "ACPI: processor: Remove unused empty stubs of some functions"
>        Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"
>
> ---------------
>
>   drivers/acpi/processor_driver.c |   6 +--
>   drivers/acpi/processor_idle.c   | 115 ++++++++++++++++------------------------
>   include/acpi/processor.h        |  34 +++++++++---
>   3 files changed, 76 insertions(+), 79 deletions(-)
>

Re: [GIT PULL] Urgent ACPI support fix for v6.18

[Rafael J. Wysocki]

On Thu, Nov 27, 2025 at 3:09 AM lihuisong (C) <lihuisong@huawei.com> wrote:
>
> Hello Rafael,
>
> 在 2025/11/26 20:54, Rafael J. Wysocki 写道:
> > Hi Linus,
> >
> > Please pull from the tag
> >
> >   git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
> >   acpi-6.18-rc8
> >
> > with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3
> >
> >   Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"
> >
> > on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
> >
> >   Linux 6.18-rc7
> >
> > to receive an urgent ACPI support fix for 6.18.
> >
> > This reverts a commit that attempted to make the code in the ACPI
> > processor driver more straightforward, but it turned out to cause
> > the kernel to crash on at least one system, along with some further
> > cleanups on top of it.
> I just found that "ACPI: processor: idle: Optimize ACPI idle driver
> registration" depends on the change
> about cpuhp_setup_state in the commit [1]. Or many CPUs don't create
> cpuidle directory.
> What is the crash? Do you have releated trace?

Yes, please see

https://lore.kernel.org/lkml/20251124200019.GIaSS5U9HhsWBotrQZ@fat_crate.local/

(from the Closes: tag in the revert commit).

Thanks!

Re: [GIT PULL] Urgent ACPI support fix for v6.18

[Longia, Amandeep Kaur]

Hi all,

On 11/27/2025 7:39 AM, lihuisong (C) wrote:
> Hello Rafael,
> 
> 在 2025/11/26 20:54, Rafael J. Wysocki 写道:
>> Hi Linus,
>>
>> Please pull from the tag
>>
>>   git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>>   acpi-6.18-rc8
>>
>> with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3
>>
>>   Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"
>>
>> on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
>>
>>   Linux 6.18-rc7
>>
>> to receive an urgent ACPI support fix for 6.18.
>>
>> This reverts a commit that attempted to make the code in the ACPI
>> processor driver more straightforward, but it turned out to cause
>> the kernel to crash on at least one system, along with some further
>> cleanups on top of it.
> I just found that "ACPI: processor: idle: Optimize ACPI idle driver 
> registration" depends on the change
> about cpuhp_setup_state in the commit [1]. Or many CPUs don't create 
> cpuidle directory.
> What is the crash? Do you have releated trace?
> 
> [1] https://lore.kernel.org/all/20240529133446.28446-2- 
> Jonathan.Cameron@huawei.com/

We have observed the same issue. After booting the system with the 
latest kernel, the sysfs path /sys/devices/system/cpu/cpu*/cpuidle does 
not exist. Bisecting between v6.18-rc7 (good) and master (bad) led us to 
the following commit:

43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3 Revert "ACPI: processor: idle: 
Optimize ACPI idle driver registration"

After debugging, we identified a code change that resolves the issue on 
our systems. Below is the code diff:

diff --git a/drivers/acpi/processor_driver.c 
b/drivers/acpi/processor_driver.c
index 7644de24d2fa..65e779be64ff 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -166,7 +166,7 @@ static int __acpi_processor_start(struct acpi_device 
*device)
         if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
                 dev_dbg(&device->dev, "CPPC data invalid or not 
present\n");

-       if (cpuidle_get_driver() == &acpi_idle_driver)
+       if (!cpuidle_get_driver() || cpuidle_get_driver() == 
&acpi_idle_driver)
                 acpi_processor_power_init(pr);

Thanks,
Amandeep

>>
>>
>> ---------------
>>
>> Rafael J. Wysocki (5):
>>        Revert "ACPI: processor: Do not expose global variable 
>> acpi_idle_driver"
>>        Revert "ACPI: processor: idle: Redefine two functions as void"
>>        Revert "ACPI: processor: idle: Rearrange declarations in header 
>> file"
>>        Revert "ACPI: processor: Remove unused empty stubs of some 
>> functions"
>>        Revert "ACPI: processor: idle: Optimize ACPI idle driver 
>> registration"
>>
>> ---------------
>>
>>   drivers/acpi/processor_driver.c |   6 +--
>>   drivers/acpi/processor_idle.c   | 115 +++++++++++++++ 
>> +------------------------
>>   include/acpi/processor.h        |  34 +++++++++---
>>   3 files changed, 76 insertions(+), 79 deletions(-)
>>

Re: [GIT PULL] Urgent ACPI support fix for v6.18

[Rafael J. Wysocki]

Hi,

On Thu, Nov 27, 2025 at 8:03 PM Longia, Amandeep Kaur
<AmandeepKaur.Longia@amd.com> wrote:
>
> Hi all,
>
> On 11/27/2025 7:39 AM, lihuisong (C) wrote:
> > Hello Rafael,
> >
> > 在 2025/11/26 20:54, Rafael J. Wysocki 写道:
> >> Hi Linus,
> >>
> >> Please pull from the tag
> >>
> >>   git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
> >>   acpi-6.18-rc8
> >>
> >> with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3
> >>
> >>   Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"
> >>
> >> on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
> >>
> >>   Linux 6.18-rc7
> >>
> >> to receive an urgent ACPI support fix for 6.18.
> >>
> >> This reverts a commit that attempted to make the code in the ACPI
> >> processor driver more straightforward, but it turned out to cause
> >> the kernel to crash on at least one system, along with some further
> >> cleanups on top of it.
> > I just found that "ACPI: processor: idle: Optimize ACPI idle driver
> > registration" depends on the change
> > about cpuhp_setup_state in the commit [1]. Or many CPUs don't create
> > cpuidle directory.
> > What is the crash? Do you have releated trace?
> >
> > [1] https://lore.kernel.org/all/20240529133446.28446-2-
> > Jonathan.Cameron@huawei.com/
>
> We have observed the same issue. After booting the system with the
> latest kernel, the sysfs path /sys/devices/system/cpu/cpu*/cpuidle does
> not exist. Bisecting between v6.18-rc7 (good) and master (bad) led us to
> the following commit:
>
> 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3 Revert "ACPI: processor: idle:
> Optimize ACPI idle driver registration"
>
> After debugging, we identified a code change that resolves the issue on
> our systems. Below is the code diff:
>
> diff --git a/drivers/acpi/processor_driver.c
> b/drivers/acpi/processor_driver.c
> index 7644de24d2fa..65e779be64ff 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -166,7 +166,7 @@ static int __acpi_processor_start(struct acpi_device
> *device)
>          if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS))
>                  dev_dbg(&device->dev, "CPPC data invalid or not
> present\n");
>
> -       if (cpuidle_get_driver() == &acpi_idle_driver)
> +       if (!cpuidle_get_driver() || cpuidle_get_driver() ==
> &acpi_idle_driver)
>                  acpi_processor_power_init(pr);
>

Thanks for this information!

One more commit needs to be reverted which I have overlooked:

8a1b5d412cb4 ACPI: processor: Update cpuidle driver check in
__acpi_processor_start()

It was a fix on top of 43ff36c4a5a5.

My bad.

Linus, I'll send a pull request with this shortly, but you may as well
revert it yourself.

[GIT PULL] One more urgent ACPI support fix for v6.18

[Rafael J. Wysocki]

Hi Linus,

Please pull from the tag

 git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
 acpi-6.18-rc8-2

with top-most commit fbf04215d9966da61feee3f4ec24dbf4544cfd0f

 Revert "ACPI: processor: Update cpuidle driver check in
__acpi_processor_start()"

on top of commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3

 Revert "ACPI: processor: idle: Optimize ACPI idle driver registration"

to receive one more urgent ACPI support fix for 6.18.

There is one more commit that needs to be reverted after reverting
problematic commit 7a8c994cbb2d ("ACPI: processor: idle: Optimize
ACPI idle driver registration"), so revert it.

Thanks!


---------------

Rafael J. Wysocki (1):
      Revert "ACPI: processor: Update cpuidle driver check in
__acpi_processor_start()"

---------------

 drivers/acpi/processor_driver.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Re: [GIT PULL] One more urgent ACPI support fix for v6.18

[pr-tracker-bot]

The pull request you sent on Thu, 27 Nov 2025 21:05:52 +0100:

> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git acpi-6.18-rc8-2

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/3fa77874b4a7ae96d4ad40623d449cef6265ae4a

Thank you!

-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/prtracker.html

Re: [GIT PULL] Urgent ACPI support fix for v6.18

[lihuisong (C)]

在 2025/11/28 3:03, Longia, Amandeep Kaur 写道:
> Hi all,
>
> On 11/27/2025 7:39 AM, lihuisong (C) wrote:
>> Hello Rafael,
>>
>> 在 2025/11/26 20:54, Rafael J. Wysocki 写道:
>>> Hi Linus,
>>>
>>> Please pull from the tag
>>>
>>> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
>>>   acpi-6.18-rc8
>>>
>>> with top-most commit 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3
>>>
>>>   Revert "ACPI: processor: idle: Optimize ACPI idle driver 
>>> registration"
>>>
>>> on top of commit ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
>>>
>>>   Linux 6.18-rc7
>>>
>>> to receive an urgent ACPI support fix for 6.18.
>>>
>>> This reverts a commit that attempted to make the code in the ACPI
>>> processor driver more straightforward, but it turned out to cause
>>> the kernel to crash on at least one system, along with some further
>>> cleanups on top of it.
>> I just found that "ACPI: processor: idle: Optimize ACPI idle driver 
>> registration" depends on the change
>> about cpuhp_setup_state in the commit [1]. Or many CPUs don't create 
>> cpuidle directory.
>> What is the crash? Do you have releated trace?
>>
>> [1] https://lore.kernel.org/all/20240529133446.28446-2- 
>> Jonathan.Cameron@huawei.com/
>
> We have observed the same issue. After booting the system with the 
> latest kernel, the sysfs path /sys/devices/system/cpu/cpu*/cpuidle 
> does not exist. Bisecting between v6.18-rc7 (good) and master (bad) 
> led us to the following commit:
>
> 43ff36c4a5a574ee83b4b0d3f3d74f09a3a8c2d3 Revert "ACPI: processor: 
> idle: Optimize ACPI idle driver registration"
>
>
Hello Amandeep,

I guess that your kernel doesn't have the following patch [1] if you 
also encountered this issue.

The __acpi_processor_start() of all CPUs are called when run 
driver_register(&acpi_processor_driver).
But acpi_processor_register_idle_driver() is called after 
driver_register(&acpi_processor_driver).
As a result, the acpi_processor_power_init() would not register cpuidle 
device and create these directory.

I tested it ok on my platform under the following modification.
Can you test it again using following modification based on kernel 
without revert any ACPI idle patch?
  I am looking forward to your reply. Thanks.
-->
diff --git a/drivers/acpi/processor_driver.c 
b/drivers/acpi/processor_driver.c
index 4b906b56186a..b56a2a228693 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -268,12 +268,12 @@ static int __init acpi_processor_driver_init(void)
                 acpi_processor_ignore_ppc_init();
         }

+       acpi_processor_register_idle_driver();
+
         result = driver_register(&acpi_processor_driver);
         if (result < 0)
                 return result;

-       acpi_processor_register_idle_driver();
-
         result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
                                            "acpi/cpu-drv:online",
                                            acpi_soft_cpu_online, NULL);
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 66d8df5a37a6..a34983abb0b9 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -1404,6 +1404,7 @@ void acpi_processor_register_idle_driver(void)
                 if (!pr)
                         continue;

+               acpi_processor_cstate_first_run_checks();
                 ret = acpi_processor_get_power_info(pr);
                 if (!ret) {
                         pr->flags.power_setup_done = 1;

[1] 
https://lore.kernel.org/all/20240529133446.28446-2-Jonathan.Cameron@huawei.com/