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[PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window

Joel Fernandes posted 3 patches 2 weeks, 4 days ago
There is a newer version of this series
kernel/rcu/tree.c      |  2 +-
kernel/rcu/tree.h      |  3 +-
kernel/rcu/tree_nocb.h | 80 ++++++++++++++----------------------------
3 files changed, 29 insertions(+), 56 deletions(-)
[PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Joel Fernandes 2 weeks, 4 days ago 
These are a few nocb related cleanup patches for the next merge window.

Also Frederic please object to the second patch ("Remove dead callback overload
handling") if you would like, but I think based on our discussion I have
implemented your suggestion, so it should be good.

Changes from v2:
- Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
  overload" as it was not needed since we removed the dead CB overload handling.
- Replaced "Add warning to detect if overload advancement is ever useful" with
  "Remove dead callback overload handling" per Frederic's feedback - instead of
  adding a warning, just remove the dead code path entirely.

nocb rcutorture scenarios passed overnight testing on my system.

Link to v2: https://lore.kernel.org/all/20260114173154.1701056-1-joelagnelf@nvidia.com/
Link to v1: https://lore.kernel.org/all/20260101163417.1065705-1-joelagnelf@nvidia.com/

Joel Fernandes (3):
  rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path
  rcu/nocb: Remove dead callback overload handling
  rcu/nocb: Extract nocb_defer_wakeup_cancel() helper

 kernel/rcu/tree.c      |  2 +-
 kernel/rcu/tree.h      |  3 +-
 kernel/rcu/tree_nocb.h | 80 ++++++++++++++----------------------------
 3 files changed, 29 insertions(+), 56 deletions(-)

-- 
2.34.1
Re: [PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Paul E. McKenney 2 weeks, 3 days ago 
On Mon, Jan 19, 2026 at 06:12:20PM -0500, Joel Fernandes wrote:
> These are a few nocb related cleanup patches for the next merge window.
> 
> Also Frederic please object to the second patch ("Remove dead callback overload
> handling") if you would like, but I think based on our discussion I have
> implemented your suggestion, so it should be good.
> 
> Changes from v2:
> - Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
>   overload" as it was not needed since we removed the dead CB overload handling.
> - Replaced "Add warning to detect if overload advancement is ever useful" with
>   "Remove dead callback overload handling" per Frederic's feedback - instead of
>   adding a warning, just remove the dead code path entirely.
> 
> nocb rcutorture scenarios passed overnight testing on my system.

I reverted three of your earlier patches in order to apply this, only
one of which I am really confident in.  Please check my -rcu tree to see
if any of the three should be added back in, and I am starting tests in
the meantime.

							Thanx, Paul

> Link to v2: https://lore.kernel.org/all/20260114173154.1701056-1-joelagnelf@nvidia.com/
> Link to v1: https://lore.kernel.org/all/20260101163417.1065705-1-joelagnelf@nvidia.com/
> 
> Joel Fernandes (3):
>   rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path
>   rcu/nocb: Remove dead callback overload handling
>   rcu/nocb: Extract nocb_defer_wakeup_cancel() helper
> 
>  kernel/rcu/tree.c      |  2 +-
>  kernel/rcu/tree.h      |  3 +-
>  kernel/rcu/tree_nocb.h | 80 ++++++++++++++----------------------------
>  3 files changed, 29 insertions(+), 56 deletions(-)
> 
> -- 
> 2.34.1
>
Re: [PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Joel Fernandes 2 weeks, 3 days ago 

On 1/21/2026 2:09 PM, Paul E. McKenney wrote:
> On Mon, Jan 19, 2026 at 06:12:20PM -0500, Joel Fernandes wrote:
>> These are a few nocb related cleanup patches for the next merge window.
>>
>> Also Frederic please object to the second patch ("Remove dead callback overload
>> handling") if you would like, but I think based on our discussion I have
>> implemented your suggestion, so it should be good.
>>
>> Changes from v2:
>> - Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
>>   overload" as it was not needed since we removed the dead CB overload handling.
>> - Replaced "Add warning to detect if overload advancement is ever useful" with
>>   "Remove dead callback overload handling" per Frederic's feedback - instead of
>>   adding a warning, just remove the dead code path entirely.
>>
>> nocb rcutorture scenarios passed overnight testing on my system.
> 
> I reverted three of your earlier patches in order to apply this, only
> one of which I am really confident in.  Please check my -rcu tree to see
> if any of the three should be added back in, and I am starting tests in
> the meantime.Age	Commit message (Expand)	Author	Files	Lines

Per your latest /dev branch
(https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/log/?h=dev),
you have the latest 3 patches:

Extract nocb_defer_wakeup_cancel() helperdev	Joel Fernandes	1	-8/+11
rcu/nocb: Remove dead callback overload handling	Joel Fernandes	1	-12/+0
rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path	Joel Fernandes	3	-36/+18

thanks,
-- 
Joel Fernandes
Re: [PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Paul E. McKenney 2 weeks, 3 days ago 
On Wed, Jan 21, 2026 at 02:13:56PM -0500, Joel Fernandes wrote:
> 
> 
> On 1/21/2026 2:09 PM, Paul E. McKenney wrote:
> > On Mon, Jan 19, 2026 at 06:12:20PM -0500, Joel Fernandes wrote:
> >> These are a few nocb related cleanup patches for the next merge window.
> >>
> >> Also Frederic please object to the second patch ("Remove dead callback overload
> >> handling") if you would like, but I think based on our discussion I have
> >> implemented your suggestion, so it should be good.
> >>
> >> Changes from v2:
> >> - Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
> >>   overload" as it was not needed since we removed the dead CB overload handling.
> >> - Replaced "Add warning to detect if overload advancement is ever useful" with
> >>   "Remove dead callback overload handling" per Frederic's feedback - instead of
> >>   adding a warning, just remove the dead code path entirely.
> >>
> >> nocb rcutorture scenarios passed overnight testing on my system.
> > 
> > I reverted three of your earlier patches in order to apply this, only
> > one of which I am really confident in.  Please check my -rcu tree to see
> > if any of the three should be added back in, and I am starting tests in
> > the meantime.Age	Commit message (Expand)	Author	Files	Lines
> 
> Per your latest /dev branch
> (https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/log/?h=dev),
> you have the latest 3 patches:
> 
> Extract nocb_defer_wakeup_cancel() helperdev	Joel Fernandes	1	-8/+11
> rcu/nocb: Remove dead callback overload handling	Joel Fernandes	1	-12/+0
> rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path	Joel Fernandes	3	-36/+18

Thank you for checking!

And just to double-check, all of the patches that I reverted are obsolete,
correct?

							Thanx, Paul
Re: [PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Joel Fernandes 2 weeks, 3 days ago 

On 1/21/2026 2:41 PM, Paul E. McKenney wrote:
> On Wed, Jan 21, 2026 at 02:13:56PM -0500, Joel Fernandes wrote:
>>
>>
>> On 1/21/2026 2:09 PM, Paul E. McKenney wrote:
>>> On Mon, Jan 19, 2026 at 06:12:20PM -0500, Joel Fernandes wrote:
>>>> These are a few nocb related cleanup patches for the next merge window.
>>>>
>>>> Also Frederic please object to the second patch ("Remove dead callback overload
>>>> handling") if you would like, but I think based on our discussion I have
>>>> implemented your suggestion, so it should be good.
>>>>
>>>> Changes from v2:
>>>> - Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
>>>>   overload" as it was not needed since we removed the dead CB overload handling.
>>>> - Replaced "Add warning to detect if overload advancement is ever useful" with
>>>>   "Remove dead callback overload handling" per Frederic's feedback - instead of
>>>>   adding a warning, just remove the dead code path entirely.
>>>>
>>>> nocb rcutorture scenarios passed overnight testing on my system.
>>>
>>> I reverted three of your earlier patches in order to apply this, only
>>> one of which I am really confident in.  Please check my -rcu tree to see
>>> if any of the three should be added back in, and I am starting tests in
>>> the meantime.Age	Commit message (Expand)	Author	Files	Lines
>>
>> Per your latest /dev branch
>> (https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/log/?h=dev),
>> you have the latest 3 patches:
>>
>> Extract nocb_defer_wakeup_cancel() helperdev	Joel Fernandes	1	-8/+11
>> rcu/nocb: Remove dead callback overload handling	Joel Fernandes	1	-12/+0
>> rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path	Joel Fernandes	3	-36/+18
> 
> Thank you for checking!
> 
> And just to double-check, all of the patches that I reverted are obsolete,
> correct?

Yes, those patches were from v2. You have correctly applied the latest v3 version.

thanks,
-- 
Joel Fernandes
Re: [PATCH -next v3 0/3] rcu/nocb: Cleanup patches for next merge window
Posted by Paul E. McKenney 2 weeks, 3 days ago 
On Wed, Jan 21, 2026 at 02:50:54PM -0500, Joel Fernandes wrote:
> 
> 
> On 1/21/2026 2:41 PM, Paul E. McKenney wrote:
> > On Wed, Jan 21, 2026 at 02:13:56PM -0500, Joel Fernandes wrote:
> >>
> >>
> >> On 1/21/2026 2:09 PM, Paul E. McKenney wrote:
> >>> On Mon, Jan 19, 2026 at 06:12:20PM -0500, Joel Fernandes wrote:
> >>>> These are a few nocb related cleanup patches for the next merge window.
> >>>>
> >>>> Also Frederic please object to the second patch ("Remove dead callback overload
> >>>> handling") if you would like, but I think based on our discussion I have
> >>>> implemented your suggestion, so it should be good.
> >>>>
> >>>> Changes from v2:
> >>>> - Dropped patch 2 "Add warning if no rcuog wake up attempt happened during
> >>>>   overload" as it was not needed since we removed the dead CB overload handling.
> >>>> - Replaced "Add warning to detect if overload advancement is ever useful" with
> >>>>   "Remove dead callback overload handling" per Frederic's feedback - instead of
> >>>>   adding a warning, just remove the dead code path entirely.
> >>>>
> >>>> nocb rcutorture scenarios passed overnight testing on my system.
> >>>
> >>> I reverted three of your earlier patches in order to apply this, only
> >>> one of which I am really confident in.  Please check my -rcu tree to see
> >>> if any of the three should be added back in, and I am starting tests in
> >>> the meantime.Age	Commit message (Expand)	Author	Files	Lines
> >>
> >> Per your latest /dev branch
> >> (https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/log/?h=dev),
> >> you have the latest 3 patches:
> >>
> >> Extract nocb_defer_wakeup_cancel() helperdev	Joel Fernandes	1	-8/+11
> >> rcu/nocb: Remove dead callback overload handling	Joel Fernandes	1	-12/+0
> >> rcu/nocb: Remove unnecessary WakeOvfIsDeferred wake path	Joel Fernandes	3	-36/+18
> > 
> > Thank you for checking!
> > 
> > And just to double-check, all of the patches that I reverted are obsolete,
> > correct?
> 
> Yes, those patches were from v2. You have correctly applied the latest v3 version.

Woo-hoo!!!  ;-)

							Thanx, Paul

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