CC: [email protected]
CC: [email protected]
TO: Frederic Weisbecker <[email protected]>
CC: "Paul E. McKenney" <[email protected]>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git 
dev.2021.01.26a
head:   142d159f544763140e0f498936bca8f71563e0e0
commit: 4fbfeec81533e6ea9811e57cc848ee30522c0517 [61/65] rcu/nocb: Forbid NOCB 
toggling on offline CPUs
:::::: branch date: 5 days ago
:::::: commit date: 5 days ago
config: sparc64-randconfig-s031-20210202 (attached as .config)
compiler: sparc64-linux-gcc (GCC) 9.3.0
reproduce:
        wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.3-215-g0fb77bb6-dirty
        # 
https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=4fbfeec81533e6ea9811e57cc848ee30522c0517
        git remote add rcu 
https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu dev.2021.01.26a
        git checkout 4fbfeec81533e6ea9811e57cc848ee30522c0517
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 
CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=sparc64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>


"sparse warnings: (new ones prefixed by >>)"
   kernel/rcu/tree.c: note: in included file:
   kernel/rcu/tree_plugin.h:1557:5: sparse: sparse: symbol 
'nocb_nobypass_lim_per_jiffy' was not declared. Should it be static?
   kernel/rcu/tree.c:1455:9: sparse: sparse: context imbalance in 
'rcu_start_this_gp' - different lock contexts for basic block
   kernel/rcu/tree.c:1867:9: sparse: sparse: context imbalance in 'rcu_gp_init' 
- different lock contexts for basic block
   kernel/rcu/tree.c:2646:9: sparse: sparse: context imbalance in 
'force_qs_rnp' - different lock contexts for basic block
   kernel/rcu/tree.c:2699:25: sparse: sparse: context imbalance in 
'rcu_force_quiescent_state' - unexpected unlock
   kernel/rcu/tree.c:2729:30: sparse: sparse: context imbalance in 'rcu_core' - 
different lock contexts for basic block
   kernel/rcu/tree.c: note: in included file:
   kernel/rcu/tree_stall.h:316:12: sparse: sparse: context imbalance in 
'rcu_print_task_stall' - unexpected unlock
   kernel/rcu/tree_stall.h:540:9: sparse: sparse: context imbalance in 
'print_other_cpu_stall' - different lock contexts for basic block
   kernel/rcu/tree.c: note: in included file:
   kernel/rcu/tree_exp.h:189:9: sparse: sparse: context imbalance in 
'__rcu_report_exp_rnp' - different lock contexts for basic block
   kernel/rcu/tree.c: note: in included file:
   kernel/rcu/tree_plugin.h:1603:16: sparse: sparse: context imbalance in 
'rcu_nocb_bypass_trylock' - wrong count at exit
   kernel/rcu/tree_plugin.h:1620:13: sparse: sparse: context imbalance in 
'rcu_nocb_lock' - wrong count at exit
   kernel/rcu/tree_plugin.h:1636:17: sparse: sparse: context imbalance in 
'rcu_nocb_unlock' - unexpected unlock
   kernel/rcu/tree_plugin.h:1649:17: sparse: sparse: context imbalance in 
'rcu_nocb_unlock_irqrestore' - unexpected unlock
   kernel/rcu/tree_plugin.h:1695:13: sparse: sparse: context imbalance in 
'wake_nocb_gp' - wrong count at exit
   kernel/rcu/tree_plugin.h:1763:9: sparse: sparse: context imbalance in 
'rcu_nocb_do_flush_bypass' - unexpected unlock
   kernel/rcu/tree_plugin.h:1778:13: sparse: sparse: context imbalance in 
'rcu_nocb_flush_bypass' - wrong count at exit
   kernel/rcu/tree_plugin.h:1929:13: sparse: sparse: context imbalance in 
'__call_rcu_nocb_wake' - wrong count at exit
   kernel/rcu/tree_plugin.h:1993:9: sparse: sparse: context imbalance in 
'do_nocb_bypass_wakeup_timer' - different lock contexts for basic block
   kernel/rcu/tree_plugin.h:2069:9: sparse: sparse: context imbalance in 
'nocb_gp_wait' - different lock contexts for basic block
   kernel/rcu/tree_plugin.h:2287:9: sparse: sparse: context imbalance in 
'nocb_cb_wait' - wrong count at exit
   kernel/rcu/tree_plugin.h:2324:13: sparse: sparse: context imbalance in 
'do_nocb_deferred_wakeup_common' - different lock contexts for basic block
   kernel/rcu/tree_plugin.h:2398:9: sparse: sparse: context imbalance in 
'rdp_offload_toggle' - wrong count at exit
>> kernel/rcu/tree_plugin.h:2430:9: sparse: sparse: context imbalance in 
>> 'rcu_nocb_rdp_deoffload' - wrong count at exit

vim +/rcu_nocb_rdp_deoffload +2430 kernel/rcu/tree_plugin.h

254e11efde66ca Frederic Weisbecker 2020-11-13  2400  
4fbfeec81533e6 Frederic Weisbecker 2021-01-28  2401  static long 
rcu_nocb_rdp_deoffload(void *arg)
254e11efde66ca Frederic Weisbecker 2020-11-13  2402  {
4fbfeec81533e6 Frederic Weisbecker 2021-01-28  2403     struct rcu_data *rdp = 
arg;
254e11efde66ca Frederic Weisbecker 2020-11-13  2404     struct rcu_segcblist 
*cblist = &rdp->cblist;
254e11efde66ca Frederic Weisbecker 2020-11-13  2405     unsigned long flags;
254e11efde66ca Frederic Weisbecker 2020-11-13  2406     int ret;
254e11efde66ca Frederic Weisbecker 2020-11-13  2407  
4fbfeec81533e6 Frederic Weisbecker 2021-01-28  2408     WARN_ON_ONCE(rdp->cpu 
!= raw_smp_processor_id());
4fbfeec81533e6 Frederic Weisbecker 2021-01-28  2409  
f759081e8f5ac6 Paul E. McKenney    2020-12-21  2410     pr_info("De-offloading 
%d\n", rdp->cpu);
254e11efde66ca Frederic Weisbecker 2020-11-13  2411  
254e11efde66ca Frederic Weisbecker 2020-11-13  2412     
rcu_nocb_lock_irqsave(rdp, flags);
254e11efde66ca Frederic Weisbecker 2020-11-13  2413  
254e11efde66ca Frederic Weisbecker 2020-11-13  2414     ret = 
rdp_offload_toggle(rdp, false, flags);
5bb39dc956f3d4 Frederic Weisbecker 2020-11-13  2415     
swait_event_exclusive(rdp->nocb_state_wq,
5bb39dc956f3d4 Frederic Weisbecker 2020-11-13  2416                           
!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB |
5bb39dc956f3d4 Frederic Weisbecker 2020-11-13  2417                             
                        SEGCBLIST_KTHREAD_GP));
69cdea873cde26 Frederic Weisbecker 2020-11-13  2418     
rcu_nocb_lock_irqsave(rdp, flags);
314202f84ddd61 Frederic Weisbecker 2020-11-13  2419     /* Make sure nocb timer 
won't stay around */
69cdea873cde26 Frederic Weisbecker 2020-11-13  2420     
WRITE_ONCE(rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_OFF);
69cdea873cde26 Frederic Weisbecker 2020-11-13  2421     
rcu_nocb_unlock_irqrestore(rdp, flags);
69cdea873cde26 Frederic Weisbecker 2020-11-13  2422     
del_timer_sync(&rdp->nocb_timer);
69cdea873cde26 Frederic Weisbecker 2020-11-13  2423  
314202f84ddd61 Frederic Weisbecker 2020-11-13  2424     /*
314202f84ddd61 Frederic Weisbecker 2020-11-13  2425      * Flush bypass. While 
IRQs are disabled and once we set
314202f84ddd61 Frederic Weisbecker 2020-11-13  2426      * 
SEGCBLIST_SOFTIRQ_ONLY, no callback is supposed to be
314202f84ddd61 Frederic Weisbecker 2020-11-13  2427      * enqueued on bypass.
314202f84ddd61 Frederic Weisbecker 2020-11-13  2428      */
314202f84ddd61 Frederic Weisbecker 2020-11-13  2429     
rcu_nocb_lock_irqsave(rdp, flags);
314202f84ddd61 Frederic Weisbecker 2020-11-13 @2430     
rcu_nocb_flush_bypass(rdp, NULL, jiffies);
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2431     
rcu_segcblist_set_flags(cblist, SEGCBLIST_SOFTIRQ_ONLY);
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2432     /*
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2433      * With 
SEGCBLIST_SOFTIRQ_ONLY, we can't use
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2434      * 
rcu_nocb_unlock_irqrestore() anymore. Theoretically we
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2435      * could set 
SEGCBLIST_SOFTIRQ_ONLY with cb unlocked and IRQs
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2436      * disabled now, but 
let's be paranoid.
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2437      */
b9ced9e1ab51ed Frederic Weisbecker 2020-11-13  2438     
raw_spin_unlock_irqrestore(&rdp->nocb_lock, flags);
314202f84ddd61 Frederic Weisbecker 2020-11-13  2439  
254e11efde66ca Frederic Weisbecker 2020-11-13  2440     return ret;
d97b078182406c Frederic Weisbecker 2020-11-13  2441  }
d97b078182406c Frederic Weisbecker 2020-11-13  2442  

:::::: The code at line 2430 was first introduced by commit
:::::: 314202f84ddd61e4d7576ef62570ad2e2d9db06b rcu/nocb: Flush bypass before 
setting SEGCBLIST_SOFTIRQ_ONLY

:::::: TO: Frederic Weisbecker <[email protected]>
:::::: CC: Paul E. McKenney <[email protected]>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

Attachment: .config.gz
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