| Message ID | 20240509074046.15629-1-qiang.zhang1211@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | rcu/nocb: Fix using smp_processor_id() in preemptible warning | expand |
On Thu, May 09, 2024 at 03:40:46PM +0800, Zqiang wrote: > Currently, the this_cpu_ptr(&rcu_data) in rcu_rdp_is_offloaded() is called > before the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" > is checked, and occurs in preemptible task context, this will trigger the > following warning. > > [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 4.111064][ T18] Call Trace: > [ 4.111064][ T18] <TASK> > [ 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 (discriminator 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 (discriminator 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] </TASK> > > This commit fix this warning by priority check the condition > "!(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 implementation") > Tested-by: kernel test robot <oliver.sang@intel.com> > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Hearing no objections, I have queued this wordsmithed version. As always, please let me know if I have messed anything up. Thanx, Paul ------------------------------------------------------------------------ commit 5271ad1de0fbcf0bd9caebcf721670c164e5fa9c Author: Zqiang <qiang.zhang1211@gmail.com> Date: Thu May 9 15:40:46 2024 +0800 rcu/nocb: Don't use smp_processor_id() in preemptible code Currently, rcu_rdp_is_offloaded() invokes this_cpu_ptr(&rcu_data) before the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" is checked. When invoked in preemptible context in preemptible kernels, this will trigger the following warning: [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 4.111064][ T18] Call Trace: [ 4.111064][ T18] <TASK> [ 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 (discriminator 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 (discriminator 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] </TASK> This commit therefore fixes this warning by checking the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" before invoking this_cpu_ptr(), thus avoiding preemptible invocations. Fixes: 8feeeba60711 ("rcu/nocb: Use kthread parking instead of ad-hoc implementation") Tested-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 31c539f09c150..475e20ebec5a5 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 == this_cpu_ptr(&rcu_data) && - !(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())) || + (!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible()) && + rdp == this_cpu_ptr(&rcu_data)) || rcu_current_is_nocb_kthread(rdp)), "Unsafe read of RCU_NOCB offloaded state" );
Le Tue, May 14, 2024 at 07:54:40AM -0700, Paul E. McKenney a écrit : > On Thu, May 09, 2024 at 03:40:46PM +0800, Zqiang wrote: > > Currently, the this_cpu_ptr(&rcu_data) in rcu_rdp_is_offloaded() is called > > before the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" > > is checked, and occurs in preemptible task context, this will trigger the > > following warning. > > > > [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > [ 4.111064][ T18] Call Trace: > > [ 4.111064][ T18] <TASK> > > [ 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 (discriminator 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 (discriminator 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] </TASK> > > > > This commit fix this warning by priority check the condition > > "!(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 implementation") > > Tested-by: kernel test robot <oliver.sang@intel.com> > > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> > > Hearing no objections, I have queued this wordsmithed version. As always, > please let me know if I have messed anything up. > > Thanx, Paul > > ------------------------------------------------------------------------ > > commit 5271ad1de0fbcf0bd9caebcf721670c164e5fa9c > Author: Zqiang <qiang.zhang1211@gmail.com> > Date: Thu May 9 15:40:46 2024 +0800 > > rcu/nocb: Don't use smp_processor_id() in preemptible code > > Currently, rcu_rdp_is_offloaded() invokes this_cpu_ptr(&rcu_data) before > the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" > is checked. When invoked in preemptible context in preemptible kernels, > this will trigger the following warning: > > [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > [ 4.111064][ T18] Call Trace: > [ 4.111064][ T18] <TASK> > [ 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 (discriminator 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 (discriminator 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] </TASK> > > This commit therefore fixes this warning by checking the condition > "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" before invoking > this_cpu_ptr(), thus avoiding preemptible invocations. > > Fixes: 8feeeba60711 ("rcu/nocb: Use kthread parking instead of ad-hoc implementation") > Tested-by: kernel test robot <oliver.sang@intel.com> > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
On Tue, May 14, 2024 at 05:18:12PM +0200, Frederic Weisbecker wrote: > Le Tue, May 14, 2024 at 07:54:40AM -0700, Paul E. McKenney a écrit : > > On Thu, May 09, 2024 at 03:40:46PM +0800, Zqiang wrote: > > > Currently, the this_cpu_ptr(&rcu_data) in rcu_rdp_is_offloaded() is called > > > before the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" > > > is checked, and occurs in preemptible task context, this will trigger the > > > following warning. > > > > > > [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > > [ 4.111064][ T18] Call Trace: > > > [ 4.111064][ T18] <TASK> > > > [ 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 (discriminator 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 (discriminator 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] </TASK> > > > > > > This commit fix this warning by priority check the condition > > > "!(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 implementation") > > > Tested-by: kernel test robot <oliver.sang@intel.com> > > > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> > > > > Hearing no objections, I have queued this wordsmithed version. As always, > > please let me know if I have messed anything up. > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 5271ad1de0fbcf0bd9caebcf721670c164e5fa9c > > Author: Zqiang <qiang.zhang1211@gmail.com> > > Date: Thu May 9 15:40:46 2024 +0800 > > > > rcu/nocb: Don't use smp_processor_id() in preemptible code > > > > Currently, rcu_rdp_is_offloaded() invokes this_cpu_ptr(&rcu_data) before > > the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" > > is checked. When invoked in preemptible context in preemptible kernels, > > this will trigger the following warning: > > > > [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > > [ 4.111064][ T18] Call Trace: > > [ 4.111064][ T18] <TASK> > > [ 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 (discriminator 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 (discriminator 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] </TASK> > > > > This commit therefore fixes this warning by checking the condition > > "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" before invoking > > this_cpu_ptr(), thus avoiding preemptible invocations. > > > > Fixes: 8feeeba60711 ("rcu/nocb: Use kthread parking instead of ad-hoc implementation") > > Tested-by: kernel test robot <oliver.sang@intel.com> > > Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Applied, thank you! Thanx, Paul
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 == this_cpu_ptr(&rcu_data) && - !(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())) || + (!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible()) && + rdp == this_cpu_ptr(&rcu_data)) || rcu_current_is_nocb_kthread(rdp)), "Unsafe read of RCU_NOCB offloaded state" );
Currently, the this_cpu_ptr(&rcu_data) in rcu_rdp_is_offloaded() is called before the condition "!(IS_ENABLED(CONFIG_PREEMPT_COUNT) && preemptible())" is checked, and occurs in preemptible task context, this will trigger the following warning. [ 4.106221][ T18] BUG: using smp_processor_id() in preemptible [00000000] code: 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), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 4.111064][ T18] Call Trace: [ 4.111064][ T18] <TASK> [ 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 (discriminator 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 (discriminator 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] </TASK> This commit fix this warning by priority check the condition "!(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 implementation") Tested-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> --- kernel/rcu/tree_plugin.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)