bisecting fixing commit since 63bbbcd8ed53c404649e0b4248c1e5d42c41ac97 building syzkaller on 34bf9440bd06034f86b5d9ac8afbf078129cbdae testing commit 63bbbcd8ed53c404649e0b4248c1e5d42c41ac97 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 738c59085950aefb7d0ea98179c5d224c5a8608752e81628deac1aefe9daa82c run #0: crashed: BUG: workqueue lockup run #1: crashed: BUG: workqueue lockup run #2: crashed: BUG: workqueue lockup run #3: crashed: BUG: workqueue lockup run #4: crashed: BUG: workqueue lockup run #5: crashed: BUG: workqueue lockup run #6: crashed: BUG: workqueue lockup run #7: crashed: BUG: workqueue lockup run #8: crashed: BUG: workqueue lockup run #9: crashed: BUG: workqueue lockup run #10: crashed: BUG: workqueue lockup run #11: crashed: BUG: workqueue lockup run #12: crashed: BUG: workqueue lockup run #13: crashed: BUG: workqueue lockup run #14: crashed: BUG: workqueue lockup run #15: crashed: INFO: rcu detected stall in sys_sendfile64 run #16: crashed: INFO: rcu detected stall in ext4_file_write_iter run #17: crashed: INFO: rcu detected stall in sys_sendfile64 run #18: crashed: INFO: rcu detected stall in sys_sendfile64 run #19: crashed: INFO: rcu detected stall in sys_sendfile64 testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: e95eea07eccf8eebd3c0d34abb2e352bb9741113757a2f0eaed572b36e73136e run #0: crashed: BUG: workqueue lockup run #1: crashed: BUG: workqueue lockup run #2: crashed: BUG: workqueue lockup run #3: crashed: BUG: workqueue lockup run #4: crashed: BUG: workqueue lockup run #5: crashed: BUG: workqueue lockup run #6: crashed: BUG: workqueue lockup run #7: crashed: BUG: workqueue lockup run #8: crashed: INFO: rcu detected stall in rw_verify_area run #9: crashed: INFO: rcu detected stall in sys_sendfile64 revisions tested: 2, total time: 36m53.68208327s (build: 26m15.55042234s, test: 9m45.62199918s) the crash still happens on HEAD commit msg: Linux 4.19.204 crash: INFO: rcu detected stall in sys_sendfile64 hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=3593, q=98) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4294951397-4294940894), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.3 R running task 26536 6503 5607 0x00000000 Call Trace: sched_show_task kernel/sched/core.c:5337 [inline] sched_show_task.cold.87+0x2f1/0x355 kernel/sched/core.c:5312 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+0xaaa/0xd89 kernel/rcu/tree.c:2682 update_process_times+0x2a/0x60 kernel/time/timer.c:1650 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:1419 [inline] __hrtimer_run_queues+0x2f7/0xab0 kernel/time/hrtimer.c:1481 hrtimer_interrupt+0x2e2/0x760 kernel/time/hrtimer.c:1539 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1071 [inline] smp_apic_timer_interrupt+0x114/0x540 arch/x86/kernel/apic/apic.c:1096 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:lock_acquire+0x1f1/0x3d0 kernel/locking/lockdep.c:3911 Code: 00 00 00 00 00 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 aa 01 00 00 48 83 3d 33 68 c6 06 00 0f 84 31 01 00 00 48 8b 7d c8 57 9d <0f> 1f 44 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b RSP: 0018:ffff8881d1f774f8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8881d739e080 RCX: 1ffff1103ae73d2a RDX: 1ffffffff1024031 RSI: 0000000000000000 RDI: 0000000000000286 RBP: ffff8881d1f77540 R08: ffff8881d739e950 R09: 0000000000000001 R10: ffff8881d739e930 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:627 [inline] is_bpf_text_address+0x2d/0xe0 kernel/bpf/core.c:545 kernel_text_address+0x79/0xf0 kernel/extable.c:152 __kernel_text_address+0xd/0x40 kernel/extable.c:107 unwind_get_return_address arch/x86/kernel/unwind_frame.c:18 [inline] unwind_get_return_address+0x61/0xa0 arch/x86/kernel/unwind_frame.c:13 __save_stack_trace+0x9c/0x100 arch/x86/kernel/stacktrace.c:45 save_stack_trace+0x1a/0x20 arch/x86/kernel/stacktrace.c:60 save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc mm/kasan/kasan.c:553 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:531 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] __do_kmalloc mm/slab.c:3725 [inline] __kmalloc+0x144/0x770 mm/slab.c:3736 kmalloc_array include/linux/slab.h:637 [inline] kcalloc include/linux/slab.h:648 [inline] iter_file_splice_write+0x12c/0xc40 fs/splice.c:693 do_splice_from fs/splice.c:852 [inline] direct_splice_actor+0x104/0x1c0 fs/splice.c:1025 splice_direct_to_actor+0x304/0x870 fs/splice.c:980 do_splice_direct+0x14c/0x270 fs/splice.c:1068 do_sendfile+0x4a6/0xe50 fs/read_write.c:1447 __do_sys_sendfile64 fs/read_write.c:1502 [inline] __se_sys_sendfile64 fs/read_write.c:1494 [inline] __x64_sys_sendfile64+0x12e/0x1e0 fs/read_write.c:1494 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x460b89 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9c906061a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 000000000052bf00 RCX: 0000000000460b89 RDX: 0000000020000000 RSI: 0000000000000003 RDI: 0000000000000003 RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 R10: 00008080fffffffe R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004f4348 R14: 00000000004b2b92 R15: 00007f9c906066bc rcu: rcu_preempt kthread starved for 10551 jiffies! g3593 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:2828 [inline] __schedule+0xdb5/0x1d40 kernel/sched/core.c:3517 schedule+0x7f/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x3ab/0xe00 kernel/time/timer.c:1818 rcu_gp_kthread+0xce6/0x23d0 kernel/rcu/tree.c:2202 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: 00 00 add %al,(%rax) 4: 00 48 89 add %cl,-0x77(%rax) 7: fa cli 8: 48 c1 ea 03 shr $0x3,%rdx c: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) 10: 0f 85 aa 01 00 00 jne 0x1c0 16: 48 83 3d 33 68 c6 06 cmpq $0x0,0x6c66833(%rip) # 0x6c66851 1d: 00 1e: 0f 84 31 01 00 00 je 0x155 24: 48 8b 7d c8 mov -0x38(%rbp),%rdi 28: 57 push %rdi 29: 9d popfq * 2a: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) <-- trapping instruction 2f: 48 8d 65 d8 lea -0x28(%rbp),%rsp 33: 5b pop %rbx 34: 41 5c pop %r12 36: 41 5d pop %r13 38: 41 5e pop %r14 3a: 41 5f pop %r15 3c: 5d pop %rbp 3d: c3 retq 3e: 65 gs 3f: 8b .byte 0x8b