Re: [PATCH v3 1/4] rcutorture: Update due to x86 not supporting none/voluntary preemption

[Boqun Feng <boqun@kernel.org>]

On Thu, Mar 05, 2026 at 12:11:46PM -0800, Paul E. McKenney wrote:
> On Thu, Mar 05, 2026 at 11:59:35AM -0800, Boqun Feng wrote:
> > On Thu, Mar 05, 2026 at 11:06:25AM -0800, Paul E. McKenney wrote:
> > > On Thu, Mar 05, 2026 at 10:22:35AM -0800, Boqun Feng wrote:
> > [...]
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TINY01 b/tools/testing/selftests/rcutorture/configs/rcu/TINY01
> > > > > index bd5ed7b0da5f0..2be53bf60d65b 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TINY01
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TINY01
> > > > > @@ -1,9 +1,9 @@
> > > > >  CONFIG_SMP=n
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_PREEMPT_DYNAMIC=n
> > > > > -CONFIG_PREEMPT_LAZY=n
> > > > 
> > > > This is the line that was introduced by the said commit, hence this
> > > > patch is still separate from that commit I think?
> > > 
> > > I *think* I have them folded/squashed correctly.
> > > 
> > > I pushed this out to my -rcu "dev" branch.  The relevant commits are,
> > > in order of increasing time of commit:
> > > 
> > > c70ac5693540 ("rcutorture: Adjust scenarios for default lazy preemption")
> > 
> > It's the commit c69ac5693540 in your "dev" branch, right?
> 
> Right you are!
> 
> > > 86126bc6d7ad ("rcutorture: Update due to x86 not supporting none/voluntary preemption")
> > > 5631c1565493 ("Revert "rcutorture: Adjust scenarios for default lazy preemption"")
> > > 6fd95cee7427 ("Revert "rcutorture: Update due to x86 not supporting none/voluntary preemption"")
> > 
> > The thing is the combination of the above 4 didn't introduce a clean
> > base in rcu/{TINY01, TREE04, TREE05, TREE06}, as shown by:
> > 
> > 	git diff 'c69ac5693540^..6fd95cee7427' -- tools/testing/selftests/rcutorture/configs/rcu/{TINY01,TREE04,TREE05,TREE06}
> > 
> > I took a look, it's because commit 86126bc6d7ad ("rcutorture: Update due
> > to x86 not supporting none/voluntary preemption") was based on commit
> > c69ac5693540, and it moved a few CONFIG_PREEMPT_LAZY configs, and when
> > it got reverted in commit 6fd95cee7427, these configs were moved back so
> > commit 5631c1565493's revert was partially reverted.
> > 
> > > 17c52d7b31a1 ("rcutorture: Update due to x86 not supporting none/voluntary preemption")
> > > 
> > 
> > A simple way to verify would be try `cherry-pick` this commit onto
> > 7.0-rc1.
> 
> Like this?
> 
> $ git reset --hard v7.0-rc1
> $ git cherry-pick 17c52d7b31a1fbec84172d279b3ab0149bc71627
> Auto-merging tools/testing/selftests/rcutorture/configs/rcu/TINY01
> Auto-merging tools/testing/selftests/rcutorture/configs/rcu/TREE04
> Auto-merging tools/testing/selftests/rcutorture/configs/rcu/TREE05
> Auto-merging tools/testing/selftests/rcutorture/configs/rcu/TREE06

Yeah, the delta is small enough so that 3-way auto-merging can handle
it. I will just apply with these resolution. Thanks!

> [detached HEAD 551d9b94e2c80] rcutorture: Update due to x86 not supporting none/voluntary preemption
>  Date: Tue Mar 3 11:28:02 2026 -0800
>  12 files changed, 29 insertions(+), 13 deletions(-)
> $ git branch lazy-1
> $ git checkout v7.0-rc1
> Previous HEAD position was 551d9b94e2c80 rcutorture: Update due to x86 not supporting none/voluntary preemption
> HEAD is now at 6de23f81a5e08 Linux 7.0-rc1
> $ git cherry-pick c69ac56935401534120ef1e40335090b973a97d2
> [detached HEAD da3c99da7a639] rcutorture: Adjust scenarios for default lazy preemption
>  Date: Wed Jan 21 10:40:30 2026 -0800
>  5 files changed, 7 insertions(+)
> 1$ git cherry-pick 86126bc6d7ad5af56c0bf8beeac12f8feaffa866
> [detached HEAD 824577abfb3b0] rcutorture: Update due to x86 not supporting none/voluntary preemption
>  Date: Tue Mar 3 11:28:02 2026 -0800
>  11 files changed, 26 insertions(+), 17 deletions(-)
> $ git diff lazy-1
> 
> Still no diff output.  What am I missing?
> 

Not important right now, but if you do:

	git range-diff 'lazy-1^..lazy-1' '17c52d7b31a1^..17c52d7b31a1'

you will see if I applied your v3 onto v7.0-rc1, I wouldn't end up
having the exact changes as the v3 has (some auto resolution happened).

Regards,
Boqun

> 							Thanx, Paul
> 
> > Regards,
> > Boqun
> > 
> > > The first was applied by Joel to the shared RCU tree, the second is in my
> > > -rcu tree, and the last three are consecutive commits in my -rcu tree.
> > > The following command gives no output, which I was interpreting as my
> > > having done it correctly.  But please double-check.
> > > 
> > > git diff 5631c1565493^..17c52d7b31a1
> > > 
> > > 							Thanx, Paul
> > > 
> > > > Regards,
> > > > Boqun
> > > > 
> > > > >  #CHECK#CONFIG_TINY_RCU=y
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > >  CONFIG_NO_HZ_IDLE=y
> > > > > @@ -12,4 +12,3 @@ CONFIG_RCU_TRACE=n
> > > > >  #CHECK#CONFIG_RCU_STALL_COMMON=n
> > > > >  CONFIG_DEBUG_LOCK_ALLOC=n
> > > > >  CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
> > > > > -CONFIG_PREEMPT_COUNT=n
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TINY02 b/tools/testing/selftests/rcutorture/configs/rcu/TINY02
> > > > > index 30439f6fc20e6..be8860342ef71 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TINY02
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TINY02
> > > > > @@ -1,5 +1,6 @@
> > > > >  CONFIG_SMP=n
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_PREEMPT_DYNAMIC=n
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRACE01 b/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
> > > > > index 18efab346381a..8fb124c28f283 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRACE01
> > > > > @@ -1,7 +1,8 @@
> > > > >  CONFIG_SMP=y
> > > > >  CONFIG_NR_CPUS=5
> > > > >  CONFIG_HOTPLUG_CPU=y
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_PREEMPT_DYNAMIC=n
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE04 b/tools/testing/selftests/rcutorture/configs/rcu/TREE04
> > > > > index 34aee1acb8662..ac857d5bcb222 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE04
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE04
> > > > > @@ -1,11 +1,12 @@
> > > > >  CONFIG_SMP=y
> > > > >  CONFIG_NR_CPUS=8
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > >  CONFIG_PREEMPT_NONE=n
> > > > > -CONFIG_PREEMPT_VOLUNTARY=y
> > > > > +CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_PREEMPT_DYNAMIC=n
> > > > > -CONFIG_PREEMPT_LAZY=n
> > > > >  #CHECK#CONFIG_TREE_RCU=y
> > > > > +#CHECK#CONFIG_PREEMPT_RCU=n
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > >  CONFIG_NO_HZ_IDLE=n
> > > > >  CONFIG_NO_HZ_FULL=y
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE05 b/tools/testing/selftests/rcutorture/configs/rcu/TREE05
> > > > > index 0513aa33c32c4..61d15b1b54d16 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE05
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE05
> > > > > @@ -1,9 +1,10 @@
> > > > >  CONFIG_SMP=y
> > > > >  CONFIG_NR_CPUS=8
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_DYNAMIC=n
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > > -CONFIG_PREEMPT_LAZY=n
> > > > >  #CHECK#CONFIG_TREE_RCU=y
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > >  CONFIG_NO_HZ_IDLE=y
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE06 b/tools/testing/selftests/rcutorture/configs/rcu/TREE06
> > > > > index cc3ea23c76557..0e090bb68a0f6 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE06
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE06
> > > > > @@ -1,10 +1,12 @@
> > > > >  CONFIG_SMP=y
> > > > >  CONFIG_NR_CPUS=8
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_DYNAMIC=n
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > > -CONFIG_PREEMPT_LAZY=n
> > > > >  #CHECK#CONFIG_TREE_RCU=y
> > > > > +#CHECK#CONFIG_PREEMPT_RCU=n
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > >  CONFIG_NO_HZ_IDLE=y
> > > > >  CONFIG_NO_HZ_FULL=n
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE10 b/tools/testing/selftests/rcutorture/configs/rcu/TREE10
> > > > > index 420632b030dc4..b2ce37861e71a 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TREE10
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE10
> > > > > @@ -6,6 +6,7 @@ CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_PREEMPT_DYNAMIC=n
> > > > >  #CHECK#CONFIG_TREE_RCU=y
> > > > > +CONFIG_PREEMPT_RCU=n
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > >  CONFIG_NO_HZ_IDLE=y
> > > > >  CONFIG_NO_HZ_FULL=n
> > > > > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
> > > > > index 5d546efa68e83..696fba9968c60 100644
> > > > > --- a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
> > > > > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
> > > > > @@ -1,6 +1,8 @@
> > > > >  CONFIG_SMP=y
> > > > >  CONFIG_NR_CPUS=8
> > > > > -CONFIG_PREEMPT_NONE=y
> > > > > +CONFIG_PREEMPT_DYNAMIC=n
> > > > > +CONFIG_PREEMPT_LAZY=y
> > > > > +CONFIG_PREEMPT_NONE=n
> > > > >  CONFIG_PREEMPT_VOLUNTARY=n
> > > > >  CONFIG_PREEMPT=n
> > > > >  CONFIG_HZ_PERIODIC=n
> > > > > 
> > > 
>