syzbot has found a reproducer for the following issue on:
HEAD commit: 7cca308cfdc0 Merge tag 'powerpc-5.15-1' of git://git.kerne.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10535915300000 kernel config: https://syzkaller.appspot.com/x/.config?x=9c582b69de20dde2 dashboard link: https://syzkaller.appspot.com/bug?extid=e2eae5639e7203360018 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10e2e533300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1294ff33300000
IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com
rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 1-....: (288 ticks this GP) idle=bdd/1/0x4000000000000000 softirq=20305/20305 fqs=5241 (t=10500 jiffies g=18249 q=67) NMI backtrace for cpu 1 CPU: 1 PID: 3254 Comm: aoe_tx0 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq.cold+0x9d/0x746 kernel/rcu/tree.c:2599 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__sanitizer_cov_trace_pc+0x5c/0x60 kernel/kcov.c:207 Code: 82 18 15 00 00 83 f8 02 75 20 48 8b 8a 20 15 00 00 8b 92 1c 15 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 <c3> 0f 1f 00 41 55 41 54 49 89 fc 55 48 bd eb 83 b5 80 46 86 c8 61 RSP: 0018:ffffc90002ccfad8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff8880206e3900 RSI: ffffffff874e536f RDI: 0000000000000003 RBP: ffff88807df1b340 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff874e5366 R11: 0000000000000000 R12: ffff88807df1b000 R13: dffffc0000000000 R14: ffff8880709ff490 R15: ffff88807df1b338 __list_del_entry include/linux/list.h:132 [inline] list_move_tail include/linux/list.h:227 [inline] fq_codel_dequeue+0x7cf/0x1f50 net/sched/sch_fq_codel.c:299 dequeue_skb net/sched/sch_generic.c:292 [inline] qdisc_restart net/sched/sch_generic.c:397 [inline] __qdisc_run+0x1ae/0x1700 net/sched/sch_generic.c:415 __dev_xmit_skb net/core/dev.c:3861 [inline] __dev_queue_xmit+0x1f6e/0x3710 net/core/dev.c:4170 tx+0x68/0xb0 drivers/block/aoe/aoenet.c:63 kthread+0x1e7/0x3b0 drivers/block/aoe/aoecmd.c:1230 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 18 15 00 00 83 f8 sbb %dl,-0x77d0000(%rip) # 0xf8830006 6: 02 75 20 add 0x20(%rbp),%dh 9: 48 8b 8a 20 15 00 00 mov 0x1520(%rdx),%rcx 10: 8b 92 1c 15 00 00 mov 0x151c(%rdx),%edx 16: 48 8b 01 mov (%rcx),%rax 19: 48 83 c0 01 add $0x1,%rax 1d: 48 39 c2 cmp %rax,%rdx 20: 76 07 jbe 0x29 22: 48 89 34 c1 mov %rsi,(%rcx,%rax,8) 26: 48 89 01 mov %rax,(%rcx) * 29: c3 retq <-- trapping instruction 2a: 0f 1f 00 nopl (%rax) 2d: 41 55 push %r13 2f: 41 54 push %r12 31: 49 89 fc mov %rdi,%r12 34: 55 push %rbp 35: 48 bd eb 83 b5 80 46 movabs $0x61c8864680b583eb,%rbp 3c: 86 c8 61