bisecting fixing commit since 125222814e7b8f84df767d6ab622aff2a6d2f234 building syzkaller on 8092f30df01f3443831725509ef5a3dae26122c0 testing commit 125222814e7b8f84df767d6ab622aff2a6d2f234 with gcc (GCC) 8.4.1 20210217 kernel signature: 6f982e04bb9b1793e3e82ec374307b6fdc73f95c976b02fa438b1327d938032e run #0: crashed: INFO: rcu detected stall in chrdev_open run #1: crashed: INFO: rcu detected stall in chrdev_open run #2: crashed: INFO: rcu detected stall in chrdev_open run #3: crashed: INFO: rcu detected stall in chrdev_open run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in chrdev_open run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in chrdev_open run #9: crashed: INFO: rcu detected stall in chrdev_open run #10: crashed: INFO: rcu detected stall in corrupted run #11: crashed: INFO: rcu detected stall in corrupted run #12: crashed: INFO: rcu detected stall in corrupted run #13: crashed: INFO: rcu detected stall in chrdev_open run #14: crashed: INFO: rcu detected stall in corrupted run #15: crashed: INFO: rcu detected stall in corrupted run #16: crashed: INFO: rcu detected stall in chrdev_open run #17: crashed: INFO: rcu detected stall in corrupted run #18: crashed: INFO: rcu detected stall in chrdev_open run #19: crashed: no output from test machine testing current HEAD 2965db2e004cf9c92b87c1f559e9812c0ae878c1 testing commit 2965db2e004cf9c92b87c1f559e9812c0ae878c1 with gcc (GCC) 8.4.1 20210217 kernel signature: 725c0d6114077e44bb885b6cc684ad7a057fda5bd5b4412d17b7e240ec2ea173 run #0: crashed: INFO: rcu detected stall in chrdev_open run #1: crashed: INFO: rcu detected stall in chrdev_open run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in chrdev_open run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in chrdev_open run #6: crashed: INFO: rcu detected stall in chrdev_open run #7: crashed: INFO: rcu detected stall in chrdev_open run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in corrupted revisions tested: 2, total time: 32m50.963274738s (build: 17m13.070753398s, test: 15m17.043045417s) the crash still happens on HEAD commit msg: Linux 4.19.188 crash: INFO: rcu detected stall in corrupted IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P7 rcu: (detected by 0, t=10502 jiffies, g=13001, q=1868) kworker/u4:0 R running task 25192 7 2 0x80000000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3715 ___preempt_schedule_notrace+0x16/0x2e rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026 rcu_read_unlock include/linux/rcupdate.h:677 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:423 [inline] batadv_nc_worker+0x3a9/0x630 net/batman-adv/network-coding.c:730 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2152 worker_thread+0x85/0xb60 kernel/workqueue.c:2295 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 kworker/u4:0 R running task 25192 7 2 0x80000000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 preempt_schedule_notrace+0x70/0x140 kernel/sched/core.c:3715 ___preempt_schedule_notrace+0x16/0x2e rcu_is_watching+0x23/0x30 kernel/rcu/tree.c:1026 rcu_read_unlock include/linux/rcupdate.h:677 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:423 [inline] batadv_nc_worker+0x3a9/0x630 net/batman-adv/network-coding.c:730 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2152 worker_thread+0x85/0xb60 kernel/workqueue.c:2295 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 rcu: rcu_preempt kthread starved for 10502 jiffies! g13001 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29160 10 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x80c/0x1f70 kernel/sched/core.c:3517 preempt_schedule_irq+0xb9/0x140 kernel/sched/core.c:3744 retint_kernel+0x1b/0x2d RIP: 0010:_raw_spin_lock_irqsave+0x11/0xd0 kernel/locking/spinlock.c:151 Code: 00 31 d2 31 f6 e8 af 71 a2 f9 48 89 df e8 47 01 a3 f9 48 8b 5d f8 58 c9 c3 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 41 54 53 <48> 89 fb 48 c7 c7 c0 24 91 89 48 89 fa 48 c1 ea 03 80 3c 02 00 0f RSP: 0018:ffff8880b59bfd18 EFLAGS: 00000287 ORIG_RAX: ffffffffffffff02 RAX: dffffc0000000000 RBX: ffff8880b59bfe98 RCX: 0000000000000000 RDX: 1ffff11016b37fd4 RSI: ffff8880b59bfe98 RDI: ffffffff89980dd8 RBP: ffff8880b59bfd28 R08: fffffbfff13301bc R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880b59bfea0 R13: ffffffff89980dd8 R14: ffff8880b59bfea8 R15: ffffffff89980e10 finish_swait+0xb9/0x290 kernel/sched/swait.c:127 rcu_gp_kthread+0xd79/0x23e0 kernel/rcu/tree.c:2202 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415