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

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jul 31, 2025 at 08:01:17PM +0800, Chen Ridong wrote:
> 
> 
> 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?

What "this series" are you responding to?  This email subject says 6.15?
Please submit the patches, properly backported, in a form that you have
tested and wish to have reviewed, otherwise we have no idea of what to
do here.

Remember, some of us get 1000+ emails a day, context matters :)

thanks,

greg k-h