bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on a41ca8fa8285754d8561dcc3ed54cca2da60eed7 testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: 261f0d5d716e5a710d6d98afb56ff4070395dd8cd920f22215af407fc54084db run #0: crashed: INFO: rcu detected stall in sys_open 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 ext4_file_read_iter run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in sys_open 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 357668399cf70ccdc0ee8967bff3448d0f4f9ae1 testing commit 357668399cf70ccdc0ee8967bff3448d0f4f9ae1 with gcc (GCC) 8.1.0 kernel signature: 5b9c1dae0242243d8e346c3b6c58d961a4bf4acafa1f8062e0e5595b137493f5 run #0: crashed: INFO: rcu detected stall in ext4_file_read_iter 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 ext4_file_read_iter run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in sys_open run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in ext4_file_read_iter revisions tested: 2, total time: 28m0.685046246s (build: 17m19.088101644s, test: 10m10.182204313s) the crash still happens on HEAD commit msg: Linux 4.19.103 crash: INFO: rcu detected stall in ext4_file_read_iter audit: type=1800 audit(1581488922.430:41): pid=7176 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=collect_data cause=failed comm="syz-executor.0" name="bus" dev="sda1" ino=16530 res=0 8021q: adding VLAN 0 to HW filter on device batadv0 hrtimer: interrupt took 42821 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=5325, q=1110) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294953553-4294943050), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.2 R running task 21560 7177 7157 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.81+0xa80/0xd67 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:168 tick_sched_timer+0x37/0xf0 kernel/time/tick-sched.c:1278 __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:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xaf/0xd0 kernel/locking/spinlock.c:184 Code: c8 07 f2 87 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 28 48 83 3d d0 04 75 01 00 74 15 48 89 df 57 9d <0f> 1f 44 00 00 eb ad e8 60 55 83 fa eb bb 0f 0b 0f 0b e8 ca b3 13 RSP: 0018:ffff8880978c5f28 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 0000000000000282 RCX: 1ffff11012dc251c RDX: 1ffffffff0fe40f9 RSI: ffff888096e128c0 RDI: 0000000000000282 RBP: ffff8880978c5f38 R08: ffff888096e128e0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff888091fea4f8 R13: ffff888091fea4f0 R14: ffff888091fea4f8 R15: ffffea0001d58c80 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline] __remove_mapping+0x360/0xbc0 mm/vmscan.c:950 shrink_page_list+0x1345/0x4360 mm/vmscan.c:1444 shrink_inactive_list+0x55f/0x15f0 mm/vmscan.c:1950 shrink_list mm/vmscan.c:2254 [inline] shrink_node_memcg+0x4ab/0x10f0 mm/vmscan.c:2519 shrink_node+0x28b/0x1170 mm/vmscan.c:2734 shrink_zones mm/vmscan.c:2966 [inline] do_try_to_free_pages+0x356/0x1170 mm/vmscan.c:3024 try_to_free_mem_cgroup_pages+0x292/0x6f0 mm/vmscan.c:3322 try_charge+0x543/0x1370 mm/memcontrol.c:2262 mem_cgroup_try_charge+0x36a/0x650 mm/memcontrol.c:5991 __add_to_page_cache_locked+0x216/0x920 mm/filemap.c:862 add_to_page_cache_lru+0x121/0x590 mm/filemap.c:928 ext4_mpage_readpages+0x382/0x14c0 fs/ext4/readpage.c:133 ext4_readpages+0xae/0x100 fs/ext4/inode.c:3364 read_pages+0xed/0x470 mm/readahead.c:123 __do_page_cache_readahead+0x35c/0x560 mm/readahead.c:211 ra_submit mm/internal.h:66 [inline] ondemand_readahead+0x42b/0xbc0 mm/readahead.c:493 page_cache_async_readahead+0x311/0x5e0 mm/readahead.c:575 generic_file_buffered_read mm/filemap.c:2123 [inline] generic_file_read_iter+0xe32/0x2050 mm/filemap.c:2385 ext4_file_read_iter+0x139/0x350 fs/ext4/file.c:77 call_read_iter include/linux/fs.h:1814 [inline] new_sync_read fs/read_write.c:406 [inline] __vfs_read+0x440/0x880 fs/read_write.c:418 integrity_kernel_read+0x128/0x200 security/integrity/iint.c:200 ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:364 [inline] ima_calc_file_shash security/integrity/ima/ima_crypto.c:393 [inline] ima_calc_file_hash+0x531/0x7f0 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:3425 [inline] path_openat+0x746/0x3c60 fs/namei.c:3537 do_filp_open+0x177/0x250 fs/namei.c:3567 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:00007f32e46bcc78 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: 00007f32e46bd6d4 R13: 00000000004fa77f R14: 00000000004dc190 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10578 jiffies! g5325 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29224 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+0xce6/0x23d0 kernel/rcu/tree.c:2202 kthread+0x324/0x3e0 kernel/kthread.c:246 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415