Hello, kernel test robot noticed "BUG:KASAN:null-ptr-deref_in_rcu_init_nohz" on: commit: 6818336557c91625024607825d736c6d2a001b4b ("BACKPORT: FROMLIST: rcu/nocb: Add an option to offload all CPUs on boot") https://chromium.googlesource.com/chromiumos/third_party/kernel chromeos-5.15 in testcase: boot compiler: gcc-13 test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G (please refer to attached dmesg/kmsg for entire log/backtrace) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot | Closes: https://lore.kernel.org/oe-lkp/202406301707.ee25630e-lkp@intel.com [ 3.205274][ T0] BUG: KASAN: null-ptr-deref in rcu_init_nohz (kernel/rcu/tree_nocb.h:1141 (discriminator 1)) [ 3.206217][ T0] Write of size 8 at addr 0000000000000000 by task swapper/0/0 [ 3.207209][ T0] [ 3.207506][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.15.36-04067-g6818336557c9 #1 [ 3.208618][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 3.209958][ T0] Call Trace: [ 3.210391][ T0] [ 3.210788][ T0] dump_stack_lvl (lib/dump_stack.c:107) [ 3.211392][ T0] ? rcu_init_nohz (kernel/rcu/tree_nocb.h:1141 (discriminator 1)) [ 3.212005][ T0] __kasan_report.cold (mm/kasan/report.c:446) [ 3.212666][ T0] ? rcu_init_nohz (kernel/rcu/tree_nocb.h:1141 (discriminator 1)) [ 3.213281][ T0] kasan_report (mm/kasan/report.c:460) [ 3.213860][ T0] kasan_check_range (mm/kasan/generic.c:173 (discriminator 1) mm/kasan/generic.c:189 (discriminator 1)) [ 3.214506][ T0] memset (mm/kasan/shadow.c:44 (discriminator 2)) [ 3.215008][ T0] rcu_init_nohz (kernel/rcu/tree_nocb.h:1141 (discriminator 1)) [ 3.215607][ T0] ? __kasan_kmalloc (mm/kasan/common.c:46 (discriminator 1) mm/kasan/common.c:434 (discriminator 1) mm/kasan/common.c:513 (discriminator 1) mm/kasan/common.c:522 (discriminator 1)) [ 3.216249][ T0] start_kernel (init/main.c:1038) [ 3.216846][ T0] secondary_startup_64_no_verify (arch/x86/kernel/head_64.S:283) [ 3.217663][ T0] [ 3.218049][ T0] ================================================================== [ 3.219076][ T0] Disabling lock debugging due to kernel taint -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki