BUG: soft lockup in tx

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 53bd76690e27 Linux 4.19.200
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11c9cce6300000
kernel config: https://syzkaller.appspot.com/x/.config?x=64e2049c2212438d
dashboard link: https://syzkaller.appspot.com/bug?extid=b9869786f84bfb6fa7f3
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=145d7c01300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1490f501300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b98697...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [aoe_tx0:3131]
Modules linked in:
irq event stamp: 15707
hardirqs last enabled at (15706): [<ffffffff81003ce4>] trace_hardirqs_on_thunk+0x1a/0x1c
hardirqs last disabled at (15707): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (794): [<ffffffff86765b45>] rcu_read_unlock_bh include/linux/rcupdate.h:717 [inline]
softirqs last enabled at (794): [<ffffffff86765b45>] __dev_queue_xmit+0x15f5/0x2e00 net/core/dev.c:3865
softirqs last disabled at (804): [<ffffffff86764732>] __dev_queue_xmit+0x1e2/0x2e00 net/core/dev.c:3773
CPU: 1 PID: 3131 Comm: aoe_tx0 Not tainted 4.19.200-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fq_codel_dequeue+0xf8/0x3740 net/sched/sch_fq_codel.c:302
Code: 74 24 40 49 8b 87 e8 02 00 00 48 89 74 24 08 48 39 c6 0f 84 b8 08 00 00 e8 35 a4 ca fa 48 8b 44 24 08 48 c1 e8 03 80 3c 18 00 <0f> 85 60 2d 00 00 48 8b 44 24 08 4c 8b 30 49 8d 46 10 48 89 84 24
RSP: 0018:ffff8880ab237a20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11016271b2f RBX: dffffc0000000000 RCX: ffffffff8697e83a
RDX: 0000000000000000 RSI: ffffffff8697de5b RDI: ffff888091b4de18
RBP: ffff8880b138d980 R08: 000000009c5b1aa3 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff8c66305b R12: 0000000000000001
R13: ffff8880b138d978 R14: ffff888091b4de10 R15: ffff8880b138d680
FS: 0000000000000000(0000) GS:ffff8880ba100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004b11d0 CR3: 0000000009e6d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
dequeue_skb net/sched/sch_generic.c:282 [inline]
qdisc_restart net/sched/sch_generic.c:385 [inline]
__qdisc_run+0x1b9/0x1640 net/sched/sch_generic.c:403
__dev_xmit_skb net/core/dev.c:3500 [inline]
__dev_queue_xmit+0x1518/0x2e00 net/core/dev.c:3807
tx+0x68/0xb0 drivers/block/aoe/aoenet.c:63
kthread+0x1d9/0x390 drivers/block/aoe/aoecmd.c:1241
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 7c113506163a1ec6157927428eddd80038d2916e
Author: Eric Dumazet <edum...@google.com>
Date: Fri Sep 3 22:03:43 2021 +0000

fq_codel: reject silly quantum parameters

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14f190e0b00000
start commit: 53bd76690e27 Linux 4.19.200
git tree: linux-4.19.y

kernel config: https://syzkaller.appspot.com/x/.config?x=64e2049c2212438d
dashboard link: https://syzkaller.appspot.com/bug?extid=b9869786f84bfb6fa7f3

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=145d7c01300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1490f501300000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: fq_codel: reject silly quantum parameters

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 756db2ba8bde Linux 4.14.249
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14c08d20b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=79558fdc04ec5505
dashboard link: https://syzkaller.appspot.com/bug?extid=47baabaa396befe0fb36

compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15927348b00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15494068b00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+47baab...@syzkaller.appspotmail.com

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [aoe_tx0:3072]
Modules linked in:
irq event stamp: 18763
hardirqs last enabled at (18762): [<ffffffff87400976>] restore_regs_and_return_to_kernel+0x0/0x2a
hardirqs last disabled at (18763): [<ffffffff874018ae>] apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:793
softirqs last enabled at (748): [<ffffffff85c3ebb6>] rcu_read_unlock_bh include/linux/rcupdate.h:721 [inline]
softirqs last enabled at (748): [<ffffffff85c3ebb6>] __dev_queue_xmit+0xc96/0x2480 net/core/dev.c:3548
softirqs last disabled at (758): [<ffffffff85c3e0cc>] __dev_queue_xmit+0x1ac/0x2480 net/core/dev.c:3455
CPU: 0 PID: 3072 Comm: aoe_tx0 Not tainted 4.14.249-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

task: ffff8880ab5ea540 task.stack: ffff8880ab4b0000
RIP: 0010:fq_codel_dequeue+0xb6/0x2c10 net/sched/sch_fq_codel.c:303
RSP: 0018:ffff8880ab4b7b28 EFLAGS: 00000a06 ORIG_RAX: ffffffffffffff10
RAX: 0000000000000000 RBX: ffff8880b2d906b8 RCX: ffff8880b2d906a8
RDX: 0000000000000000 RSI: ffff8880b2d906b8 RDI: ffff888092e08658
RBP: ffff8880b2d906c0 R08: 0000000000000001 R09: 000000000004850f
R10: ffff8880ab5eae18 R11: ffff8880ab5ea540 R12: ffff8880b2d90480
R13: dffffc0000000000 R14: ffff8880b2d90480 R15: ffff888092e08650
FS: 0000000000000000(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fff88df2888 CR3: 00000000b30c1000 CR4: 00000000003406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

dequeue_skb net/sched/sch_generic.c:148 [inline]
qdisc_restart net/sched/sch_generic.c:241 [inline]
__qdisc_run+0x322/0xe00 net/sched/sch_generic.c:257
__dev_xmit_skb net/core/dev.c:3231 [inline]
__dev_queue_xmit+0x13ac/0x2480 net/core/dev.c:3489
tx+0x68/0xa0 drivers/block/aoe/aoenet.c:63
kthread+0x1b9/0x350 drivers/block/aoe/aoecmd.c:1259
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: 48 c1 e8 03 42 80 3c 28 00 0f 85 3f 23 00 00 48 8b 04 24 4c 8b 38 49 8d 47 10 48 89 84 24 80 00 00 00 48 c1 e8 03 42 0f b6 04 28 <84> c0 74 08 3c 03 0f 8e 05 23 00 00 41 8b 5f 10 85 db 0f 8e 98
----------------
Code disassembly (best guess):
0: 48 c1 e8 03 shr $0x3,%rax
4: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
9: 0f 85 3f 23 00 00 jne 0x234e
f: 48 8b 04 24 mov (%rsp),%rax
13: 4c 8b 38 mov (%rax),%r15
16: 49 8d 47 10 lea 0x10(%r15),%rax
1a: 48 89 84 24 80 00 00 mov %rax,0x80(%rsp)
21: 00
22: 48 c1 e8 03 shr $0x3,%rax
26: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
* 2b: 84 c0 test %al,%al <-- trapping instruction
2d: 74 08 je 0x37
2f: 3c 03 cmp $0x3,%al
31: 0f 8e 05 23 00 00 jle 0x233c
37: 41 8b 5f 10 mov 0x10(%r15),%ebx
3b: 85 db test %ebx,%ebx
3d: 0f .byte 0xf
3e: 8e .byte 0x8e
3f: 98 cwtl