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[ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] c= ode: rcuop/0/18 [ 4.107796][ T18] caller is debug_smp_processor_id (lib/smp_processor_id.c:= 61) [ 4.108547][ T18] CPU: 0 PID: 18 Comm: rcuop/0 Not tainted 6.9.0-rc2-00079-= g4c66bc7cacc0 #1 [ 4.109667][ T18] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BI= OS 1.16.2-debian-1.16.2-1 04/01/2014 [ 4.111064][ T18] Call Trace: [ 4.111064][ T18] [ 4.111064][ T18] dump_stack_lvl (lib/dump_stack.c:116) [ 4.111064][ T18] dump_stack (lib/dump_stack.c:124) [ 4.111064][ T18] check_preemption_disabled (arch/x86/include/asm/preempt.h= :84 (discriminator 15) lib/smp_processor_id.c:53 (discriminator 15)) [ 4.111064][ T18] debug_smp_processor_id (lib/smp_processor_id.c:61) [ 4.111064][ T18] rcu_rdp_is_offloaded (kernel/rcu/tree_plugin.h:27 (discri= minator 1)) [ 4.111064][ T18] nocb_cb_wait (kernel/rcu/tree_nocb.h:936 (discriminator 2= )) [ 4.111064][ T18] rcu_nocb_cb_kthread (kernel/rcu/tree_nocb.h:983 (discrimi= nator 1)) [ 4.111064][ T18] ? nocb_cb_wait (kernel/rcu/tree_nocb.h:976) [ 4.111064][ T18] kthread (kernel/kthread.c:388) [ 4.111064][ T18] ? kthread (kernel/kthread.c:373 (discriminator 2)) [ 4.111064][ T18] ? kthread_complete_and_exit (kernel/kthread.c:341) [ 4.111064][ T18] ret_from_fork (arch/x86/kernel/process.c:153) [ 4.111064][ T18] ? kthread_complete_and_exit (kernel/kthread.c:341) [ 4.111064][ T18] ret_from_fork_asm (arch/x86/entry/entry_64.S:256) [ 4.111064][ T18] This commit fix this warning by priority check the condition=20 "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" , to ensure whether the this_cpu_ptr(&rcu_data) can be executed in rcu_rdp_is_offloaded(). Fixes: 8feeeba60711 ("rcu/nocb: Use kthread parking instead of ad-hoc imple= mentation") Tested-by: kernel test robot Signed-off-by: Zqiang Reviewed-by: Frederic Weisbecker --- kernel/rcu/tree_plugin.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 340bbefe5f65..1bb73466a8a9 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -28,8 +28,8 @@ static bool rcu_rdp_is_offloaded(struct rcu_data *rdp) !(lockdep_is_held(&rcu_state.barrier_mutex) || (IS_ENABLED(CONFIG_HOTPLUG_CPU) && lockdep_is_cpus_held()) || rcu_lockdep_is_held_nocb(rdp) || - (rdp =3D=3D this_cpu_ptr(&rcu_data) && - !(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())) || + (!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible()) && + rdp =3D=3D this_cpu_ptr(&rcu_data)) || rcu_current_is_nocb_kthread(rdp)), "Unsafe read of RCU_NOCB offloaded state" ); --=20 2.17.1