bisecting fixing commit since 7ca4ad5ba886557b67d42242a80f303c3a99ded1 building syzkaller on 9dcc1191cb8089742cc226a8b64f992ae505cc22 testing commit 7ca4ad5ba886557b67d42242a80f303c3a99ded1 with gcc (GCC) 8.1.0 kernel signature: 4aafb7f673188e2c06b0f35e896068aa839f9f8fd51fca00957e616cab64bed3 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 corrupted run #3: crashed: INFO: rcu detected stall in new_sync_read run #4: crashed: INFO: rcu detected stall in sys_open run #5: crashed: INFO: rcu detected stall in new_sync_read run #6: crashed: INFO: rcu detected stall in sys_open run #7: crashed: INFO: rcu detected stall in new_sync_read run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in corrupted testing current HEAD 90568ecf561540fa330511e21fcd823b0c3829c6 testing commit 90568ecf561540fa330511e21fcd823b0c3829c6 with gcc (GCC) 8.1.0 kernel signature: 8f4f0013f8c2b6720ce17196fe351d485647d7d0f0f088b6adf790db162f4b58 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 new_sync_read run #3: crashed: INFO: rcu detected stall in new_sync_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 corrupted run #8: crashed: INFO: rcu detected stall in new_sync_read run #9: boot failed: can't ssh into the instance revisions tested: 2, total time: 31m27.889389759s (build: 13m47.051298053s, test: 17m18.315707559s) the crash still happens on HEAD commit msg: Merge tag 'kvm-5.6-2' of git://git.kernel.org/pub/scm/virt/kvm/kvm crash: INFO: rcu detected stall in new_sync_read rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=7997, q=431) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294955456-4294944953), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.0 R running task 22320 8726 8664 0x80004002 Call Trace: sched_show_task.cold.99+0x2ee/0x35d kernel/sched/core.c:5954 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline] check_cpu_stall kernel/rcu/tree_stall.h:558 [inline] rcu_pending kernel/rcu/tree.c:3030 [inline] rcu_sched_clock_irq.cold.86+0xb55/0xc8b kernel/rcu/tree.c:2276 update_process_times+0x23/0x50 kernel/time/timer.c:1726 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:171 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1314 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x32f/0xb50 kernel/time/hrtimer.c:1579 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1641 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1110 [inline] smp_apic_timer_interrupt+0x163/0x5f0 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_clear_bit_unlock_is_negative_byte arch/x86/include/asm/bitops.h:101 [inline] RIP: 0010:clear_bit_unlock_is_negative_byte include/asm-generic/bitops/instrumented-lock.h:75 [inline] RIP: 0010:unlock_page+0xe8/0x1a0 mm/filemap.c:1294 Code: 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 9d 00 00 00 49 8b 04 24 a8 01 74 5d be 08 00 00 00 48 89 df e8 68 97 1a 00 80 23 fe 78 07 5b 41 5c 41 5d 5d c3 48 89 df 31 f6 e8 61 fc ff RSP: 0018:ffffc90002c65db0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000001 RBX: ffffea000195f600 RCX: ffffffff818555e8 RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffea000195f600 RBP: ffffc90002c65dc8 R08: fffff9400032bec1 R09: fffff9400032bec1 R10: fffff9400032bec0 R11: ffffea000195f607 R12: ffffea000195f600 R13: ffffea000195f608 R14: ffffea000195f600 R15: dffffc0000000000 shrink_page_list+0x1541/0x3890 mm/vmscan.c:1429 shrink_inactive_list+0x44f/0xc70 mm/vmscan.c:1945 shrink_list mm/vmscan.c:2164 [inline] shrink_lruvec+0x702/0xf20 mm/vmscan.c:2482 shrink_node_memcgs mm/vmscan.c:2671 [inline] shrink_node+0x356/0x1670 mm/vmscan.c:2777 shrink_zones mm/vmscan.c:2980 [inline] do_try_to_free_pages+0x352/0x1330 mm/vmscan.c:3033 try_to_free_mem_cgroup_pages+0x2a3/0x850 mm/vmscan.c:3355 try_charge+0x5b0/0x1310 mm/memcontrol.c:2455 mem_cgroup_try_charge+0x137/0x590 mm/memcontrol.c:6367 __add_to_page_cache_locked+0x306/0xa40 mm/filemap.c:844 add_to_page_cache_lru+0x153/0x580 mm/filemap.c:921 ext4_mpage_readpages+0x3bd/0x1c70 fs/ext4/readpage.c:259 ext4_readpages+0xc8/0xf0 fs/ext4/inode.c:3245 read_pages+0xed/0x510 mm/readahead.c:126 __do_page_cache_readahead+0x411/0x520 mm/readahead.c:212 ra_submit mm/internal.h:62 [inline] ondemand_readahead+0x428/0xbe0 mm/readahead.c:492 page_cache_async_readahead+0x2ff/0x5a0 mm/readahead.c:574 generic_file_buffered_read mm/filemap.c:2037 [inline] generic_file_read_iter+0xf15/0x15a0 mm/filemap.c:2302 ext4_file_read_iter+0x194/0x540 fs/ext4/file.c:131 call_read_iter include/linux/fs.h:1895 [inline] new_sync_read+0x3fa/0x7d0 fs/read_write.c:414 __vfs_read+0x94/0x110 fs/read_write.c:427 integrity_kernel_read+0x13a/0x1f0 security/integrity/iint.c:200 ima_calc_file_hash_tfm+0x280/0x360 security/integrity/ima/ima_crypto.c:360 ima_calc_file_shash security/integrity/ima/ima_crypto.c:391 [inline] ima_calc_file_hash+0x170/0x460 security/integrity/ima/ima_crypto.c:456 ima_collect_measurement+0x3f6/0x4f0 security/integrity/ima/ima_api.c:249 process_measurement+0x955/0x16f0 security/integrity/ima/ima_main.c:326 ima_file_check+0xc8/0x110 security/integrity/ima/ima_main.c:442 do_last fs/namei.c:3494 [inline] path_openat+0x949/0x2d40 fs/namei.c:3607 do_filp_open+0x171/0x240 fs/namei.c:3637 do_sys_openat2+0x2e0/0x510 fs/open.c:1149 do_sys_open+0x90/0xe0 fs/open.c:1165 ksys_open include/linux/syscalls.h:1386 [inline] __do_sys_open fs/open.c:1171 [inline] __se_sys_open fs/open.c:1169 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1169 do_syscall_64+0xca/0x5f0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a9e9 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:00007fce0243bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a9e9 RDX: 0000000000000000 RSI: 0000000000141042 RDI: 0000000020000100 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fce0243c6d4 R13: 00000000004fe41f R14: 00000000004df4a8 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10597 jiffies! g7997 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29360 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3386 [inline] __schedule+0x8a9/0x1970 kernel/sched/core.c:4082 schedule+0xc3/0x2b0 kernel/sched/core.c:4156 schedule_timeout+0x38b/0xad0 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1658 [inline] rcu_gp_kthread+0x9f2/0x1890 kernel/rcu/tree.c:1818 kthread+0x331/0x3f0 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 sched: RT throttling activated