[syzbot] WARNING in cake_dequeue

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 521a547ced64 Linux 6.0-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1267c108880000
kernel config: https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb
dashboard link: https://syzkaller.appspot.com/bug?extid=1a58ef288b4f7a56adbf
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1a58ef...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 12003 at net/sched/sch_cake.c:2093 cake_dequeue+0x2188/0x3cb0 net/sched/sch_cake.c:2093
Modules linked in:
CPU: 0 PID: 12003 Comm: syz-executor.4 Not tainted 6.0.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
RIP: 0010:cake_dequeue+0x2188/0x3cb0 net/sched/sch_cake.c:2093
Code: 66 39 c5 0f 42 e8 e8 a7 a1 f1 f9 89 ee bf 00 04 00 00 e8 3b 9e f1 f9 66 81 fd 00 04 0f b7 dd 0f 86 a1 ef ff ff e8 88 a1 f1 f9 <0f> 0b e9 95 ef ff ff 31 ed e9 83 e8 ff ff e8 75 a1 f1 f9 48 8b 84
RSP: 0018:ffffc90000007cf0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 000000000000ffff RCX: 0000000000000100
RDX: ffff888033c15880 RSI: ffffffff878a6798 RDI: 0000000000000003
RBP: 000000000000ffff R08: 0000000000000003 R09: 0000000000000400
R10: 000000000000ffff R11: 0000000000000001 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88803ef01aa0 R15: ffff88803ef00000
FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2eb23000 CR3: 000000000bc8e000 CR4: 0000000000350ef0
Call Trace:
<IRQ>
dequeue_skb net/sched/sch_generic.c:292 [inline]
qdisc_restart net/sched/sch_generic.c:397 [inline]
__qdisc_run+0x1ae/0x1710 net/sched/sch_generic.c:415
qdisc_run include/net/pkt_sched.h:126 [inline]
qdisc_run include/net/pkt_sched.h:123 [inline]
net_tx_action+0x71f/0xd20 net/core/dev.c:5086
__do_softirq+0x1d3/0x9c6 kernel/softirq.c:571
invoke_softirq kernel/softirq.c:445 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1106
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:check_kcov_mode kernel/kcov.c:166 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0xd/0x60 kernel/kcov.c:200
Code: 00 00 e9 86 c0 81 02 66 0f 1f 44 00 00 48 8b be a8 01 00 00 e8 b4 ff ff ff 31 c0 c3 90 65 8b 05 19 66 86 7e 89 c1 48 8b 34 24 <81> e1 00 01 00 00 65 48 8b 14 25 80 6f 02 00 a9 00 01 ff 00 74 0e
RSP: 0018:ffffc9000a98f758 EFLAGS: 00000246
RAX: 0000000080000001 RBX: 00007fee55929000 RCX: 0000000080000001
RDX: ffff888033c15880 RSI: ffffffff81b45ece RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea0001b5bac8
R13: ffffea0001b5bac0 R14: dffffc0000000000 R15: ffff888077a6a940
zap_pte_range mm/memory.c:1508 [inline]
zap_pmd_range mm/memory.c:1575 [inline]
zap_pud_range mm/memory.c:1604 [inline]
zap_p4d_range mm/memory.c:1625 [inline]
unmap_page_range+0xd1e/0x3cc0 mm/memory.c:1646
unmap_single_vma+0x196/0x360 mm/memory.c:1694
unmap_vmas+0x18c/0x310 mm/memory.c:1731
exit_mmap+0x1b8/0x490 mm/mmap.c:3116
__mmput+0x122/0x4b0 kernel/fork.c:1187
mmput+0x56/0x60 kernel/fork.c:1208
exit_mm kernel/exit.c:510 [inline]
do_exit+0x9e2/0x29b0 kernel/exit.c:782
do_group_exit+0xd2/0x2f0 kernel/exit.c:925
get_signal+0x238c/0x2610 kernel/signal.c:2857
arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869
exit_to_user_mode_loop kernel/entry/common.c:166 [inline]
exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:294
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fee55a89409
Code: Unable to access opcode bytes at RIP 0x7fee55a893df.
RSP: 002b:00007fee56bfb218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fee55b9bf88 RCX: 00007fee55a89409
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fee55b9bf88
RBP: 00007fee55b9bf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fee55b9bf8c
R13: 00007fffab12ee9f R14: 00007fee56bfb300 R15: 0000000000022000
</TASK>
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: e9 86 c0 81 02 jmpq 0x281c08d
7: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
d: 48 8b be a8 01 00 00 mov 0x1a8(%rsi),%rdi
14: e8 b4 ff ff ff callq 0xffffffcd
19: 31 c0 xor %eax,%eax
1b: c3 retq
1c: 90 nop
1d: 65 8b 05 19 66 86 7e mov %gs:0x7e866619(%rip),%eax # 0x7e86663d
24: 89 c1 mov %eax,%ecx
26: 48 8b 34 24 mov (%rsp),%rsi
* 2a: 81 e1 00 01 00 00 and $0x100,%ecx <-- trapping instruction
30: 65 48 8b 14 25 80 6f mov %gs:0x26f80,%rdx
37: 02 00
39: a9 00 01 ff 00 test $0xff0100,%eax
3e: 74 0e je 0x4e


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.