bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on a41ca8fa8285754d8561dcc3ed54cca2da60eed7 testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: ff4727d680117a143f0292ce9619690cd46dea9c run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in ext4_file_read_iter run #2: crashed: INFO: rcu detected stall in sys_open run #3: crashed: INFO: rcu detected stall in sys_open run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in sys_open run #6: crashed: INFO: rcu detected stall in ext4_file_read_iter run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in ext4_file_read_iter run #9: crashed: INFO: rcu detected stall in sys_open testing current HEAD dcd888983542055210f5e68f1b1f1f8fe11a369a testing commit dcd888983542055210f5e68f1b1f1f8fe11a369a with gcc (GCC) 8.1.0 kernel signature: 2dbec47f82307c0a7230236eb88ad79bdc43b31c run #0: crashed: INFO: rcu detected stall in sys_open run #1: crashed: INFO: rcu detected stall in sys_open run #2: crashed: INFO: rcu detected stall in sys_open run #3: crashed: INFO: rcu detected stall in ext4_file_read_iter run #4: crashed: INFO: rcu detected stall in ext4_file_read_iter run #5: crashed: INFO: rcu detected stall in ext4_file_read_iter run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in ext4_file_read_iter run #8: crashed: INFO: rcu detected stall in sys_open run #9: crashed: INFO: rcu detected stall in sys_open revisions tested: 2, total time: 27m44.555101762s (build: 17m15.226806942s, test: 9m55.203466946s) the crash still happens on HEAD commit msg: Linux 4.19.95 crash: INFO: rcu detected stall in sys_open IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bond: link becomes ready hrtimer: interrupt took 29972 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=5209, q=308) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294953190-4294942687), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.4 R running task 21608 7204 7182 0x80000002 Call Trace: sched_show_task.cold.86+0x2ee/0x35d kernel/sched/core.c:5338 print_other_cpu_stall kernel/rcu/tree.c:1430 [inline] check_cpu_stall kernel/rcu/tree.c:1557 [inline] __rcu_pending kernel/rcu/tree.c:3293 [inline] rcu_pending kernel/rcu/tree.c:3336 [inline] rcu_check_callbacks.cold.82+0xa71/0xd3d kernel/rcu/tree.c:2682 update_process_times+0x2a/0x60 kernel/time/timer.c:1638 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:164 tick_sched_timer+0x37/0xf0 kernel/time/tick-sched.c:1274 __run_hrtimer kernel/time/hrtimer.c:1401 [inline] __hrtimer_run_queues+0x2f7/0xab0 kernel/time/hrtimer.c:1463 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1521 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline] smp_apic_timer_interrupt+0x114/0x540 arch/x86/kernel/apic/apic.c:1092 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:893 RIP: 0010:loop2+0x1d7/0x39e Code: 19 c4 63 7b f0 f0 0b 41 31 cf 45 31 f5 c4 63 7b f0 f0 06 41 21 c7 45 31 f5 c4 63 7b f0 e2 0d 41 31 cf c4 63 7b f0 f2 16 89 d6 <45> 31 e6 c4 63 7b f0 e2 02 44 03 44 3c 20 44 09 d6 45 31 e6 41 89 RSP: 0018:ffff8880a86cf200 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 000000008f1e93a6 RBX: 00000000fd46eb1b RCX: 0000000013d74209 RDX: 00000000d8be710c RSI: 00000000d8be710c RDI: 0000000000000180 RBP: ffff8880a86cf4a8 R08: 00000000f4a01c08 R09: 000000009d758f30 R10: 00000000a089b0ac R11: 00000000fc97c0bc R12: 000000008866c5f3 R13: 0000000061a44adb R14: 00000000f9c43362 R15: 000000009dc7c30b sha256_avx2_update+0x10/0x20 arch/x86/crypto/sha256_ssse3_glue.c:235 crypto_shash_update+0xd0/0x2e0 crypto/shash.c:126 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:373 [inline] ima_calc_file_shash security/integrity/ima/ima_crypto.c:393 [inline] ima_calc_file_hash+0x511/0x7f0 security/integrity/ima/ima_crypto.c:458 ima_collect_measurement+0x3fc/0x520 security/integrity/ima/ima_api.c:231 process_measurement+0xb0e/0x14b0 security/integrity/ima/ima_main.c:284 ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:391 do_last fs/namei.c:3422 [inline] path_openat+0x6dd/0x3c00 fs/namei.c:3534 do_filp_open+0x177/0x250 fs/namei.c:3564 do_sys_open+0x1dd/0x350 fs/open.c:1088 __do_sys_open fs/open.c:1106 [inline] __se_sys_open fs/open.c:1101 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1101 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459f49 Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fdb19bddc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f49 RDX: 0000000000000000 RSI: 0000000000141042 RDI: 0000000020000100 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fdb19bde6d4 R13: 00000000004fa77f R14: 00000000004dc190 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10545 jiffies! g5209 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29208 10 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2826 [inline] __schedule+0x78c/0x1c10 kernel/sched/core.c:3515 schedule+0x7f/0x1b0 kernel/sched/core.c:3559 schedule_timeout+0x3ab/0xda0 kernel/time/timer.c:1806 rcu_gp_kthread+0xcf8/0x23d0 kernel/rcu/tree.c:2202 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415