Re: Patch "Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"" has been added to the 6.15-stable tree

[Chen Ridong <chenridong@huaweicloud.com>]

On 2025/7/29 22:33, Greg KH wrote:
> On Tue, Jul 29, 2025 at 09:22:10PM +0800, Chen Ridong wrote:
>>
>>
>> On 2025/7/24 17:43, Greg KH wrote:
>>> On Thu, Jul 24, 2025 at 05:38:52PM +0800, Chen Ridong wrote:
>>>>
>>>>
>>>> On 2025/7/23 13:06, Greg KH wrote:
>>>>> On Wed, Jul 23, 2025 at 09:01:43AM +0800, Chen Ridong wrote:
>>>>>>
>>>>>>
>>>>>> On 2025/7/22 20:38, Greg KH wrote:
>>>>>>> On Tue, Jul 22, 2025 at 08:25:49PM +0800, Chen Ridong wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 2025/7/22 20:18, Greg KH wrote:
>>>>>>>>> On Tue, Jul 22, 2025 at 09:29:13AM +0800, Chen Ridong wrote:
>>>>>>>>>>
>>>>>>>>>>> This is a note to let you know that I've just added the patch titled
>>>>>>>>>>>
>>>>>>>>>>>     Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"
>>>>>>>>>>>
>>>>>>>>>>> to the 6.15-stable tree which can be found at:
>>>>>>>>>>>     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>>>>>>>>>>>
>>>>>>>>>>> The filename of the patch is:
>>>>>>>>>>>      revert-cgroup_freezer-cgroup_freezing-check-if-not-f.patch
>>>>>>>>>>> and it can be found in the queue-6.15 subdirectory.
>>>>>>>>>>>
>>>>>>>>>>> If you, or anyone else, feels it should not be added to the stable tree, please let <stable@vger.kernel.org> know about it.
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> The patch ("sched,freezer: Remove unnecessary warning in __thaw_task") should also be merged to
>>>>>>>>>> prevent triggering another warning in __thaw_task().
>>>>>>>>>
>>>>>>>>> What is the git commit id of that change in Linus's tree?
>>>>>>>>>
>>>>>>>>> thanks,
>>>>>>>>>
>>>>>>>>> greg k-h
>>>>>>>>
>>>>>>>> 9beb8c5e77dc10e3889ff5f967eeffba78617a88 ("sched,freezer: Remove unnecessary warning in __thaw_task")
>>>>>>>
>>>>>>> Thanks, but that didn't apply to 6.1.y or 6.6.y.  Shouldn't it also go
>>>>>>> there as that's what this revert was applied back to.
>>>>>>>
>>>>>>> greg k-h
>>>>>>
>>>>>> Hi Greg,
>>>>>>
>>>>>> The commit 9beb8c5e77dc ("sched,freezer: Remove unnecessary warning...") should be merged together
>>>>>> with 14a67b42cb6f ("Revert "cgroup_freezer: cgroup_freezing: Check if not frozen"") to avoid the
>>>>>> warning for 6.1.y or 6.6.y.
>>>>>
>>>>> Ok, but 9beb8c5e77dc does not apply properly there.  Can you please
>>>>> provide a working backport?
>>>>>
>>>>> thanks,
>>>>>
>>>>> greg k-h
>>>>
>>>> IIUC, we need to backport these two commits together:
>>>> 1.commit 23ab79e8e469 ("freezer,sched: Do not restore saved_state of a thawed task")
>>>> 2.commit 9beb8c5e77dc ("sched,freezer: Remove unnecessary warning...").
>>>>
>>>> After applying these prerequisites, the required change becomes minimal:
>>>>
>>>> diff --git a/kernel/freezer.c b/kernel/freezer.c
>>>> index 4fad0e6fca64..288d1cce1fc4 100644
>>>> --- a/kernel/freezer.c
>>>> +++ b/kernel/freezer.c
>>>> @@ -196,7 +196,7 @@ void __thaw_task(struct task_struct *p)
>>>>         unsigned long flags, flags2;
>>>>
>>>>         spin_lock_irqsave(&freezer_lock, flags);
>>>> -       if (WARN_ON_ONCE(freezing(p)))
>>>> +       if (!frozen(p))
>>>>                 goto unlock;
>>>>
>>>>         if (lock_task_sighand(p, &flags2)) {
>>>>
>>>> Would you like me to prepare and submit this patch for the stable branches (6.6.y and 6.1.y)?
>>>
>>> Yes, please send me the missing patches as a series for each branch that
>>> needs them.
>>>
>>> thanks,
>>>
>>> greg k-h
>>
>> Hi Greg and maintainers,
>>
>> I've sent the patch series for 6.6.y. Backporting commit 9beb8c5e77dc ("sched,freezer: Remove
>> unnecessary warning...") requires 4 patches for 6.6.y, and the backport to 6.1.y would be even more
>> complex.
>>
>> As an alternative, I'm considering addressing the warning directly with the patch I mentioned
>> previously. What are your thoughts on this approach?
>>
>> The new patch:
>>
>> diff --git a/kernel/freezer.c b/kernel/freezer.c
>> index 4fad0e6fca64..288d1cce1fc4 100644
>> --- a/kernel/freezer.c
>> +++ b/kernel/freezer.c
>> @@ -196,7 +196,7 @@ void __thaw_task(struct task_struct *p)
>>         unsigned long flags, flags2;
>>
>>         spin_lock_irqsave(&freezer_lock, flags);
>> -       if (WARN_ON_ONCE(freezing(p)))
>> +       if (!frozen(p))
>>                 goto unlock;
>>
>>         if (lock_task_sighand(p, &flags2)) {
>>
> 
> I have no idea, sorry, please work with the developers/maintainers of
> the original change and get their approval.  But normally, we do NOT
> want one-off changes being made to older kernel trees unless it has to
> be done, as that makes maintaining them much much much harder over time.
> 
> thanks,
> 
> greg k-h

Hi, developers/maintainers,

Could you please review this series for 6.6.y?

Best regards,
Ridong