bisecting fixing commit since ef244c3088856cf048c77231653b4c92a7b2213c building syzkaller on a41ca8fa8285754d8561dcc3ed54cca2da60eed7 testing commit ef244c3088856cf048c77231653b4c92a7b2213c with gcc (GCC) 8.1.0 kernel signature: 01e04551424cd04c1b5d7aabcad18840e31cf8bcc3613ea21e8ee34cce35e087 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 corrupted 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 sys_open run #9: crashed: INFO: rcu detected stall in corrupted testing current HEAD dda0e2920330128e0dbdeb11c8f25031aa40b11c testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0 kernel signature: b9f0b069ec021c793898f3a6fe4c2b0fad96fd1f86c28a89c021479720cd8cf5 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 __vfs_read run #4: crashed: INFO: rcu detected stall in sys_open 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 ext4_file_read_iter run #8: crashed: INFO: rcu detected stall in sys_open run #9: crashed: INFO: rcu detected stall in ext4_file_read_iter revisions tested: 2, total time: 30m29.731184131s (build: 17m33.201066279s, test: 12m15.227147166s) the crash still happens on HEAD commit msg: Linux 4.19.114 crash: INFO: rcu detected stall in ext4_file_read_iter audit: type=1800 audit(1586676590.786:30): pid=7348 uid=0 auid=0 ses=8 subj=system_u:system_r:kernel_t:s0 op=collect_data cause=failed comm="syz-executor.2" name="bus" dev="sda1" ino=15706 res=0 IPVS: ftp: loaded support on port[0] = 21 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 0, t=10502 jiffies, g=6365, q=155) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294964962-4294954459), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.2 R running task 24488 7368 6359 0x80000000 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:ext4_es_lookup_extent+0x469/0x960 fs/ext4/extents_status.c:824 Code: 04 00 00 49 8b 96 80 06 00 00 48 8b 45 d0 48 89 f1 48 c1 e9 03 44 89 60 18 48 b8 00 00 00 00 00 fc ff df 0f b6 0c 01 48 89 f0 <83> e0 07 83 c0 03 38 c8 7c 08 84 c9 0f 85 6d 04 00 00 8b 43 1c 4c RSP: 0018:ffff888090036b00 EFLAGS: 00000a03 ORIG_RAX: ffffffffffffff13 RAX: ffff88807145d6e4 RBX: ffff88807145d6c8 RCX: 0000000000000000 RDX: ffff8882163c4600 RSI: ffff88807145d6e4 RDI: ffff88809a06a7c0 RBP: ffff888090036b40 R08: ffffed100e30eb62 R09: ffffed100e30eb61 R10: ffffed100e30eb61 R11: ffff888071875b0b R12: 0000000000000000 R13: ffff8880718756b0 R14: ffff88809a06a140 R15: ffff888071875b08 ext4_map_blocks+0x13e/0x16b0 fs/ext4/inode.c:539 ext4_mpage_readpages+0x8c9/0x1560 fs/ext4/readpage.c:181 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+0x121f/0x20d0 mm/filemap.c:2385 ext4_file_read_iter+0x139/0x350 fs/ext4/file.c:78 call_read_iter include/linux/fs.h:1815 [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:1085 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 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:00007fc0e96cfc78 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: 00007fc0e96d06d4 R13: 00000000004fa77f R14: 00000000004dc190 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10560 jiffies! g6365 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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+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