Re: [RFC PATCH v2 17/20] rcutorture: Add a test config to torture test low RCU_DYNTICKS width

[Paul E. McKenney]

On Fri, Jul 21, 2023 at 08:58:53AM +0100, Valentin Schneider wrote:
> On 20/07/23 21:00, Paul E. McKenney wrote:
> > On Thu, Jul 20, 2023 at 12:53:05PM -0700, Paul E. McKenney wrote:
> >> On Thu, Jul 20, 2023 at 05:30:53PM +0100, Valentin Schneider wrote:
> >> > diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE11 b/tools/testing/selftests/rcutorture/configs/rcu/TREE11
> >> > new file mode 100644
> >> > index 0000000000000..aa7274efd9819
> >> > --- /dev/null
> >> > +++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE11
> >> > @@ -0,0 +1,19 @@
> >> > +CONFIG_SMP=y
> >> > +CONFIG_NR_CPUS=8
> >> > +CONFIG_PREEMPT_NONE=n
> >> > +CONFIG_PREEMPT_VOLUNTARY=y
> >> > +CONFIG_PREEMPT=n
> >> > +CONFIG_PREEMPT_DYNAMIC=n
> >> > +#CHECK#CONFIG_TREE_RCU=y
> >> > +CONFIG_HZ_PERIODIC=n
> >> > +CONFIG_NO_HZ_IDLE=n
> >> > +CONFIG_NO_HZ_FULL=y
> >> > +CONFIG_RCU_TRACE=y
> >> > +CONFIG_RCU_FANOUT=4
> >> > +CONFIG_RCU_FANOUT_LEAF=3
> >> > +CONFIG_DEBUG_LOCK_ALLOC=n
> >> > +CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
> >> > +CONFIG_RCU_EXPERT=y
> >> > +CONFIG_RCU_EQS_DEBUG=y
> >> > +CONFIG_RCU_LAZY=y
> >> > +CONFIG_RCU_DYNTICKS_BITS=2
> >>
> >> Why not just add this last line to the existing TREE04 scenario?
> >> That would ensure that it gets tested regularly without extending the
> >> time required to run a full set of rcutorture tests.
> >
> > Please see below for the version of this patch that I am running overnight
> > tests with.  Does this one work for you?
> 
> Yep that's fine with me. I only went with a separate test file as wasn't
> sure how new test options should be handled (merged into existing tests vs
> new tests created), and didn't want to negatively impact TREE04 or
> TREE06. If merging into TREE04 is preferred, then I'll do just that and
> carry this path moving forwards.

Things worked fine for this one-hour-per-scenario test run on my laptop,
except for the CONFIG_SMP=n runs, which all got build errors like the
following.

							Thanx, Paul

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

In file included from ./include/linux/container_of.h:5,
                 from ./include/linux/list.h:5,
                 from ./include/linux/swait.h:5,
                 from ./include/linux/completion.h:12,
                 from ./include/linux/crypto.h:15,
                 from arch/x86/kernel/asm-offsets.c:9:
./include/linux/context_tracking_state.h:56:61: error: ‘struct context_tracking’ has no member named ‘state’
   56 | #define CT_STATE_SIZE (sizeof(((struct context_tracking *)0)->state) * BITS_PER_BYTE)
      |                                                             ^~
./include/linux/build_bug.h:78:56: note: in definition of macro ‘__static_assert’
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/context_tracking_state.h:73:1: note: in expansion of macro ‘static_assert’
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      | ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:61:29: note: in expansion of macro ‘CT_STATE_SIZE’
   61 | #define RCU_DYNTICKS_START (CT_STATE_SIZE - CONFIG_RCU_DYNTICKS_BITS)
      |                             ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:70:29: note: in expansion of macro ‘RCU_DYNTICKS_START’
   70 | #define CONTEXT_WORK_END   (RCU_DYNTICKS_START - 1)
      |                             ^~~~~~~~~~~~~~~~~~
./include/linux/context_tracking_state.h:74:16: note: in expansion of macro ‘CONTEXT_WORK_END’
   74 |               (CONTEXT_WORK_END  + 1 - CONTEXT_WORK_START) +
      |                ^~~~~~~~~~~~~~~~
./include/linux/context_tracking_state.h:56:61: error: ‘struct context_tracking’ has no member named ‘state’
   56 | #define CT_STATE_SIZE (sizeof(((struct context_tracking *)0)->state) * BITS_PER_BYTE)
      |                                                             ^~
./include/linux/build_bug.h:78:56: note: in definition of macro ‘__static_assert’
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/context_tracking_state.h:73:1: note: in expansion of macro ‘static_assert’
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      | ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:62:29: note: in expansion of macro ‘CT_STATE_SIZE’
   62 | #define RCU_DYNTICKS_END   (CT_STATE_SIZE - 1)
      |                             ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:75:16: note: in expansion of macro ‘RCU_DYNTICKS_END’
   75 |               (RCU_DYNTICKS_END  + 1 - RCU_DYNTICKS_START) ==
      |                ^~~~~~~~~~~~~~~~
./include/linux/context_tracking_state.h:56:61: error: ‘struct context_tracking’ has no member named ‘state’
   56 | #define CT_STATE_SIZE (sizeof(((struct context_tracking *)0)->state) * BITS_PER_BYTE)
      |                                                             ^~
./include/linux/build_bug.h:78:56: note: in definition of macro ‘__static_assert’
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/context_tracking_state.h:73:1: note: in expansion of macro ‘static_assert’
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      | ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:61:29: note: in expansion of macro ‘CT_STATE_SIZE’
   61 | #define RCU_DYNTICKS_START (CT_STATE_SIZE - CONFIG_RCU_DYNTICKS_BITS)
      |                             ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:75:40: note: in expansion of macro ‘RCU_DYNTICKS_START’
   75 |               (RCU_DYNTICKS_END  + 1 - RCU_DYNTICKS_START) ==
      |                                        ^~~~~~~~~~~~~~~~~~
./include/linux/context_tracking_state.h:56:61: error: ‘struct context_tracking’ has no member named ‘state’
   56 | #define CT_STATE_SIZE (sizeof(((struct context_tracking *)0)->state) * BITS_PER_BYTE)
      |                                                             ^~
./include/linux/build_bug.h:78:56: note: in definition of macro ‘__static_assert’
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/context_tracking_state.h:73:1: note: in expansion of macro ‘static_assert’
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      | ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:76:15: note: in expansion of macro ‘CT_STATE_SIZE’
   76 |               CT_STATE_SIZE);
      |               ^~~~~~~~~~~~~
./include/linux/context_tracking_state.h:73:15: error: expression in static assertion is not an integer
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      |               ^
./include/linux/build_bug.h:78:56: note: in definition of macro ‘__static_assert’
   78 | #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
      |                                                        ^~~~
./include/linux/context_tracking_state.h:73:1: note: in expansion of macro ‘static_assert’
   73 | static_assert((CONTEXT_STATE_END + 1 - CONTEXT_STATE_START) +
      | ^~~~~~~~~~~~~
make[2]: *** [scripts/Makefile.build:116: arch/x86/kernel/asm-offsets.s] Error 1
make[1]: *** [/home/git/linux-rcu-1/Makefile:1275: prepare0] Error 2
make[1]: *** Waiting for unfinished jobs....
  LD      /home/git/linux-rcu-1/tools/objtool/objtool-in.o
  LINK    /home/git/linux-rcu-1/tools/objtool/objtool
make: *** [Makefile:234: __sub-make] Error 2