bisecting fixing commit since 8a61716ff2ab23eddd1f7a05a075a374e4d0c3d4 building syzkaller on 7ff74a98320355d2a8c097333827b6565dbf64b9 testing commit 8a61716ff2ab23eddd1f7a05a075a374e4d0c3d4 with gcc (GCC) 8.1.0 kernel signature: f4fa50a8061212258e9e861a9e2eb36edfc9f616 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in sys_sendfile64 run #2: crashed: INFO: rcu detected stall in corrupted run #3: crashed: INFO: rcu detected stall in sys_sendfile64 run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in corrupted run #6: crashed: INFO: rcu detected stall in ext4_file_write_iter run #7: crashed: INFO: rcu detected stall in rw_verify_area run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in corrupted testing current HEAD 6afa873170a612b2b9e392c19c523ed8aae6fbc9 testing commit 6afa873170a612b2b9e392c19c523ed8aae6fbc9 with gcc (GCC) 8.1.0 kernel signature: f1a2415f696a6ef589181023613e10c66992acc0 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in ext4_file_write_iter run #2: crashed: INFO: rcu detected stall in ext4_file_write_iter run #3: crashed: INFO: rcu detected stall in sys_sendfile64 run #4: crashed: INFO: rcu detected stall in corrupted run #5: crashed: INFO: rcu detected stall in ext4_file_write_iter run #6: crashed: INFO: rcu detected stall in sys_sendfile64 run #7: crashed: INFO: rcu detected stall in corrupted run #8: crashed: INFO: rcu detected stall in corrupted run #9: crashed: INFO: rcu detected stall in sys_sendfile64 revisions tested: 2, total time: 22m26.111617825s (build: 11m32.264728193s, test: 10m2.419219921s) the crash still happens on HEAD commit msg: Merge tag 'linux-kselftest-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest crash: INFO: rcu detected stall in sys_sendfile64 IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=5549, q=409) 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 26600 7433 7316 0x00004000 Call Trace: sched_show_task.cold.100+0x2ee/0x35d kernel/sched/core.c:5954 print_other_cpu_stall kernel/rcu/tree_stall.h:410 [inline] check_cpu_stall kernel/rcu/tree_stall.h:538 [inline] rcu_pending kernel/rcu/tree.c:2827 [inline] rcu_sched_clock_irq.cold.89+0xb2e/0xc5e kernel/rcu/tree.c:2271 update_process_times+0x23/0x50 kernel/time/timer.c:1726 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:167 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1310 __run_hrtimer kernel/time/hrtimer.c:1517 [inline] __hrtimer_run_queues+0x332/0xb50 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+0x16f/0x600 arch/x86/kernel/apic/apic.c:1135 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:update_stack_state+0x485/0x5e0 arch/x86/kernel/unwind_frame.c:239 Code: ea 03 80 3c 02 00 0f 85 12 01 00 00 4d 8b 24 24 e9 b0 fe ff ff 49 8d 7d 38 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 e0 00 00 00 48 8b 85 68 ff ff ff 49 c7 45 58 00 RSP: 0018:ffff888098a9f3c0 EFLAGS: 00000a02 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff888098a9ff48 RCX: 1ffff11013153e00 RDX: 1ffff11013153eb5 RSI: ffff888098a9ff58 RDI: ffff888098a9f5a8 RBP: ffff888098a9f488 R08: 1ffff11013153eb8 R09: ffff888098a9f520 R10: ffff888098a9f5a8 R11: ffff888098a9f5cf R12: ffff888098a9f560 R13: ffff888098a9f570 R14: 1ffff11013153e80 R15: ffff888098a9f5b0 unwind_next_frame.part.6+0x1ab/0xa20 arch/x86/kernel/unwind_frame.c:311 unwind_next_frame+0x3e/0x50 arch/x86/kernel/unwind_frame.c:265 arch_stack_walk+0x8a/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x82/0xb0 kernel/stacktrace.c:123 save_stack+0x21/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc.constprop.9+0xc7/0xd0 mm/kasan/common.c:513 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:527 __do_kmalloc mm/slab.c:3656 [inline] __kmalloc+0x164/0x790 mm/slab.c:3665 kmalloc_array include/linux/slab.h:598 [inline] kcalloc include/linux/slab.h:609 [inline] iter_file_splice_write+0x12c/0xb80 fs/splice.c:702 do_splice_from fs/splice.c:863 [inline] direct_splice_actor+0x107/0x1c0 fs/splice.c:1037 splice_direct_to_actor+0x348/0x960 fs/splice.c:992 do_splice_direct+0x14c/0x270 fs/splice.c:1080 do_sendfile+0x481/0xd10 fs/read_write.c:1464 __do_sys_sendfile64 fs/read_write.c:1519 [inline] __se_sys_sendfile64 fs/read_write.c:1511 [inline] __x64_sys_sendfile64+0x12e/0x1e0 fs/read_write.c:1511 do_syscall_64+0xd0/0x600 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457f79 Code: ad b8 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 b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fd857e48c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000457f79 RDX: 0000000020000000 RSI: 0000000000000003 RDI: 0000000000000003 RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 00008080fffffffe R11: 0000000000000246 R12: 00007fd857e496d4 R13: 00000000004c4e6e R14: 00000000004d8b98 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10554 jiffies! g5549 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29376 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x856/0x1910 kernel/sched/core.c:4081 schedule+0xc3/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x38b/0xad0 kernel/time/timer.c:1895 rcu_gp_fqs_loop kernel/rcu/tree.c:1661 [inline] rcu_gp_kthread+0x997/0x1820 kernel/rcu/tree.c:1821 kthread+0x334/0x3f0 kernel/kthread.c:255 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352