Re: [syzbot] [net?] INFO: rcu detected stall in unix_release

[Jakub Kicinski]

Hi Vladimir, any ideas for this one?
The bisection looks pooped, FWIW, looks like a taprio inf loop.

On Sun, 13 Aug 2023 13:45:59 -0700 syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d0378ae6d16c Merge branch 'enetc-probe-fix'
> git tree:       net
> console output: https://syzkaller.appspot.com/x/log.txt?x=1052ea2ba80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=fa5bd4cd5ab6259d
> dashboard link: https://syzkaller.appspot.com/bug?extid=a3618a167af2021433cd
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1152c6eda80000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13b1eddda80000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/c893f52cd6ab/disk-d0378ae6.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/dfb7a8b86a99/vmlinux-d0378ae6.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/cb9134e0a22c/bzImage-d0378ae6.xz
> 
> The issue was bisected to:
> 
> commit c2368b19807affd7621f7c4638cd2e17fec13021
> Author: Jiri Pirko <jiri@xxxxxxxxxx>
> Date:   Fri Jul 29 07:10:35 2022 +0000
> 
>     net: devlink: introduce "unregistering" mark and use it during devlinks iteration
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=134f1179a80000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=10cf1179a80000
> console output: https://syzkaller.appspot.com/x/log.txt?x=174f1179a80000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a3618a167af2021433cd@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: c2368b19807a ("net: devlink: introduce "unregistering" mark and use it during devlinks iteration")
> 
> rcu: INFO: rcu_preempt self-detected stall on CPU
> rcu: 	0-....: (10499 ticks this GP) idle=9774/1/0x4000000000000000 softirq=8757/8758 fqs=5219
> rcu: 	         hardirqs   softirqs   csw/system
> rcu: 	 number:        1          0            0
> rcu: 	cputime:    26308      26181           17   ==> 52490(ms)
> rcu: 	(t=10500 jiffies g=8417 q=457 ncpus=2)
> CPU: 0 PID: 5047 Comm: syz-executor224 Not tainted 6.5.0-rc4-syzkaller-00212-gd0378ae6d16c #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
> RIP: 0010:taprio_dequeue_tc_priority+0x263/0x4b0 net/sched/sch_taprio.c:798
> Code: 8b 74 24 10 89 ef 44 89 f6 e8 29 b8 2c f9 44 39 f5 0f 84 40 ff ff ff e8 2b bd 2c f9 49 83 ff 0f 0f 87 e1 01 00 00 48 8b 04 24 <0f> b6 00 38 44 24 36 7c 08 84 c0 0f 85 bf 01 00 00 8b 33 8b 4c 24
> RSP: 0018:ffffc90000007d60 EFLAGS: 00000293
> RAX: ffffed10047a4a72 RBX: ffff888023d25394 RCX: 0000000000000100
> RDX: ffff888028efbb80 RSI: ffffffff88594af5 RDI: 0000000000000004
> RBP: 0000000000000008 R08: 0000000000000004 R09: 0000000000000008
> R10: 0000000000000000 R11: ffffc90000007ff8 R12: 0000000000000010
> R13: ffff88802d19ab60 R14: 0000000000000000 R15: 0000000000000001
> FS:  0000555555857380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020000600 CR3: 000000002cdd1000 CR4: 00000000003506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <IRQ>
>  taprio_dequeue+0x12e/0x5f0 net/sched/sch_taprio.c:868
>  dequeue_skb net/sched/sch_generic.c:292 [inline]
>  qdisc_restart net/sched/sch_generic.c:397 [inline]
>  __qdisc_run+0x1c4/0x19d0 net/sched/sch_generic.c:415
>  qdisc_run include/net/pkt_sched.h:125 [inline]
>  qdisc_run include/net/pkt_sched.h:122 [inline]
>  net_tx_action+0x71e/0xc80 net/core/dev.c:5049
>  __do_softirq+0x218/0x965 kernel/softirq.c:553
>  invoke_softirq kernel/softirq.c:427 [inline]
>  __irq_exit_rcu kernel/softirq.c:632 [inline]
>  irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644
>  sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1109
>  </IRQ>
>  <TASK>
>  asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645
> RIP: 0010:unwind_next_frame+0x5ba/0x2020 arch/x86/kernel/unwind_orc.c:517
> Code: 31 02 00 00 41 80 fe 04 0f 84 08 0c 00 00 41 80 fe 05 0f 85 d7 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 14 24 48 c1 ea 03 <80> 3c 02 00 0f 85 42 19 00 00 48 89 c8 4d 8b 7d 38 48 ba 00 00 00
> RSP: 0018:ffffc90003b9f748 EFLAGS: 00000a02
> RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffffff8f3ed5c8
> RDX: 1ffff92000773efe RSI: 0000000000000001 RDI: ffffffff8ec31910
> RBP: ffffc90003b9f800 R08: ffffffff8f3ed646 R09: ffffffff8f3ed5cc
> R10: ffffc90003b9f7b8 R11: 000000000000d9e9 R12: ffffc90003b9f808
> R13: ffffc90003b9f7b8 R14: 0000000000000005 R15: 0000000000000000
>  arch_stack_walk+0x8b/0xf0 arch/x86/kernel/stacktrace.c:25
>  stack_trace_save+0x96/0xd0 kernel/stacktrace.c:122
>  kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
>  kasan_set_track+0x25/0x30 mm/kasan/common.c:52
>  kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
>  ____kasan_slab_free mm/kasan/common.c:236 [inline]
>  ____kasan_slab_free+0x15e/0x1b0 mm/kasan/common.c:200
>  kasan_slab_free include/linux/kasan.h:162 [inline]
>  slab_free_hook mm/slub.c:1792 [inline]
>  slab_free_freelist_hook+0x10b/0x1e0 mm/slub.c:1818
>  slab_free mm/slub.c:3801 [inline]
>  kmem_cache_free+0xf0/0x490 mm/slub.c:3823
>  sk_prot_free net/core/sock.c:2122 [inline]
>  __sk_destruct+0x49e/0x770 net/core/sock.c:2216
>  sk_destruct+0xc2/0xf0 net/core/sock.c:2231
>  __sk_free+0xc4/0x3a0 net/core/sock.c:2242
>  sk_free+0x7c/0xa0 net/core/sock.c:2253
>  sock_put include/net/sock.h:1975 [inline]
>  unix_release_sock+0xa76/0xf70 net/unix/af_unix.c:668
>  unix_release+0x88/0xe0 net/unix/af_unix.c:1065
>  __sock_release+0xcd/0x290 net/socket.c:654
>  sock_close+0x1c/0x20 net/socket.c:1386
>  __fput+0x3fd/0xac0 fs/file_table.c:384
>  task_work_run+0x14d/0x240 kernel/task_work.c:179
>  resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0x210/0x240 kernel/entry/common.c:204
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
>  syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
>  do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7fc3bb116ef7
> Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
> RSP: 002b:00007ffd1d8ead88 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
> RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007fc3bb116ef7
> RDX: 0000000000000000 RSI: 0000000000008933 RDI: 0000000000000004
> RBP: 00007ffd1d8ead90 R08: 0000000000000008 R09: 0000000000000004
> R10: 000000000000000b R11: 0000000000000246 R12: 00007ffd1d8eafc0
> R13: 00003faaaaaaaaaa R14: 00007ffd1d8eaff0 R15: 00007fc3bb164376
>  </TASK>
> 
> 
> ---
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> 
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> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> If the bug is already fixed, let syzbot know by replying with:
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> 
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> 
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