On Wed, 6 Dec 2017 13:47:38 -0800 "Paul E. McKenney" paulmck@linux.vnet.ibm.com wrote:

On Wed, Dec 06, 2017 at 09:56:36PM +0100, Arnd Bergmann wrote:

...

On Wed, Dec 6, 2017 at 8:24 PM, kernelci.org bot bot@kernelci.org wrote:

...

stable-rc/linux-3.18.y build: 184 builds: 3 failed, 181 passed, 3 errors (v3.18.86-23-g635374e30005) Full Build Summary: https://kernelci.org/build/stable-rc/branch/linux-3.18.y/kernel/v3.18.86-23-... Tree: stable-rc Branch: linux-3.18.y Git Describe: v3.18.86-23-g635374e30005 Git Commit: 635374e300051ce71a548aff2c469fbda3910c21 Git URL: http://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git Built: 4 unique architectures

Build Failures Detected:

x86: gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) defconfig+CONFIG_LKDTM=y FAIL i386_defconfig FAIL x86_64_defconfig FAIL

Errors Detected:

x86: gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) defconfig+CONFIG_LKDTM=y 1 error i386_defconfig 1 error x86_64_defconfig 1 error Errors summary: 2 kprobes.c:(.text+0x91f42): undefined reference to `synchronize_rcu_tasks' 1 kprobes.c:(.text+0x80dc8): undefined reference to `synchronize_rcu_tasks'

Same as v4.9, caused by 98efb31592b4 ("kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y").

Looks to me like they are both missing 7e42776d5ed1f ("rcu: Drive TASKS_RCU directly off of PREEMPT"), which is shown below.

Masami, how would you like to proceed?

I think the commit 98efb31592b4 is an improvement patch, so do not need to pull on 3.18. Maybe 4.14 is easy to pull because we just need below patch. but for 3.18, it needs more depending patches, doesn't it?

Thank you,

					Thanx, Paul

---

commit 7e42776d5ed1fe9a941ed8876c5d15cd7cf5d89f Author: Paul E. McKenney paulmck@linux.vnet.ibm.com Date: Thu May 25 08:05:00 2017 -0700

rcu: Drive TASKS_RCU directly off of PREEMPT

The actual use of TASKS_RCU is only when PREEMPT, otherwise RCU-sched is used instead. This commit therefore makes synchronize_rcu_tasks() and call_rcu_tasks() available always, but mapped to synchronize_sched() and call_rcu_sched(), respectively, when !PREEMPT. This approach also allows some #ifdefs to be removed from rcutorture. Reported-by: Ingo Molnar mingo@kernel.org Signed-off-by: Paul E. McKenney paulmck@linux.vnet.ibm.com Reviewed-by: Masami Hiramatsu mhiramat@kernel.org Acked-by: Ingo Molnar mingo@kernel.org

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index f816fc72b51e..c3f380befdd7 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -58,8 +58,6 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func); void call_rcu_bh(struct rcu_head *head, rcu_callback_t func); void call_rcu_sched(struct rcu_head *head, rcu_callback_t func); void synchronize_sched(void); -void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); -void synchronize_rcu_tasks(void); void rcu_barrier_tasks(void); #ifdef CONFIG_PREEMPT_RCU @@ -176,10 +174,14 @@ extern struct srcu_struct tasks_rcu_exit_srcu; rcu_all_qs(); \ rcu_note_voluntary_context_switch_lite(t); \ } while (0) +void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func); +void synchronize_rcu_tasks(void); #else /* #ifdef CONFIG_TASKS_RCU */ #define TASKS_RCU(x) do { } while (0) #define rcu_note_voluntary_context_switch_lite(t) do { } while (0) #define rcu_note_voluntary_context_switch(t) rcu_all_qs() +#define call_rcu_tasks call_rcu_sched +#define synchronize_rcu_tasks synchronize_sched #endif /* #else #ifdef CONFIG_TASKS_RCU */ /** diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig index be90c945063f..9210379c0353 100644 --- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig @@ -69,8 +69,7 @@ config TREE_SRCU This option selects the full-fledged version of SRCU. config TASKS_RCU

• bool
• default n

• def_bool PREEMPT select SRCU help This option enables a task-based RCU implementation that uses

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index b8f7f8ce8575..b284c861a511 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -696,8 +696,6 @@ static struct rcu_torture_ops sched_ops = { .name = "sched" }; -#ifdef CONFIG_TASKS_RCU

/*

• Definitions for RCU-tasks torture testing.

*/ @@ -735,24 +733,11 @@ static struct rcu_torture_ops tasks_ops = { .name = "tasks" }; -#define RCUTORTURE_TASKS_OPS &tasks_ops,

static bool __maybe_unused torturing_tasks(void) { return cur_ops == &tasks_ops; } -#else /* #ifdef CONFIG_TASKS_RCU */

-#define RCUTORTURE_TASKS_OPS

-static bool __maybe_unused torturing_tasks(void) -{

• return false;

-}

-#endif /* #else #ifdef CONFIG_TASKS_RCU */

/*

• RCU torture priority-boost testing. Runs one real-time thread per
• CPU for moderate bursts, repeatedly registering RCU callbacks and

@@ -1749,7 +1734,7 @@ rcu_torture_init(void) int firsterr = 0; static struct rcu_torture_ops *torture_ops[] = { &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,

• &sched_ops, RCUTORTURE_TASKS_OPS
  

• &sched_ops, &tasks_ops,
  

  };

if (!torture_init_begin(torture_type, verbose, &torture_runnable)) diff --git a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt index 9ad3f89c8dc7..af6fca03602f 100644 --- a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt +++ b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt @@ -69,11 +69,11 @@ CONFIG_RCU_TORTURE_TEST_RUNNABLE CONFIG_PREEMPT_RCU CONFIG_TREE_RCU CONFIG_TINY_RCU +CONFIG_TASKS_RCU These are controlled by CONFIG_PREEMPT and/or CONFIG_SMP. CONFIG_SRCU -CONFIG_TASKS_RCU Selected by CONFIG_RCU_TORTURE_TEST, so cannot disable.