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Date:   Tue, 15 Nov 2022 19:14:42 +0800
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To:     Wei Chen <harperchen1110@gmail.com>
Cc:     clm@fb.com, josef@toxicpanda.com, dsterba@suse.com,
        linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        osandov@fb.com, sweettea-kernel@dorminy.me,
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From:   Qu Wenruo <quwenruo.btrfs@gmx.com>
Subject: Re: WARNING in _btrfs_ioctl_set_received_subvol
In-Reply-To: <CAO4mrfcnodR8csMs7s8SCgE5k7LEk2emhEJSaKs7+Ye3NzaXGQ@mail.gmail.com>
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On 2022/11/15 18:48, Wei Chen wrote:
> Dear Linux developers,
> 
> Thank you for the advice. Please find the crash report in the upstream
> release v6.0.0 below.

You know what? Even using your v6.0.0 report, it's just doing more harm 
than good.

Your reports never include the most important part

- The 6.0 report is the worst.
   panic_on_warn hides the original line number.

- The v5.15.76 report only make sense if one digs the full console
   output.

   I just spend several minutes on the v5.15.76 report, and you know
   what? The line number points to btrfs_abort_transaction().
   And what caused the abort transaction?

   Nope, your email just cut it and only shows the WARN() line.

   Then more time spent on your console output, you know what?
   Fault injection:

  FAULT_INJECTION: forcing a failure.
  name failslab, interval 1, probability 0, space 0, times 0
  CPU: 1 PID: 29222 Comm: syz-executor.0 Not tainted 5.15.76 #5
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
  Call Trace:
   <TASK>
   dump_stack_lvl+0x8d/0xcf
   should_fail+0x13c/0x160
   should_failslab+0x5/0x10
   kmem_cache_alloc+0x6a/0x360
   ? __mutex_unlock_slowpath+0x3c/0x280
   btrfs_uuid_tree_remove+0x6e/0x270
   ? btrfs_record_root_in_trans+0x6f/0x90
   ? start_transaction+0x115/0x970
   _btrfs_ioctl_set_received_subvol+0x1d7/0x430
   ? btrfs_ioctl+0x2154/0x3d50
   btrfs_ioctl+0x2154/0x3d50
   ? __fget_files+0x141/0x260
   ? do_vfs_ioctl+0x150/0xaa0
   ? btrfs_ioctl_get_supported_features+0x40/0x40
   ? __x64_sys_ioctl+0xb6/0x100
   __x64_sys_ioctl+0xb6/0x100
   do_syscall_64+0x34/0xb0
   entry_SYSCALL_64_after_hwframe+0x61/0xcb
  RIP: 0033:0x4697f9
  Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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

  RSP: 002b:00007f41ffc26c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9
  RDX: 0000000020072c40 RSI: 00000000c0c09425 RDI: 0000000000000005
  RBP: 00007f41ffc26c80 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
  R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffd3c817900

   So, the whole situation is, we abort transaction because we hit an
   ENOMEM.


Thankfully the following patch should end the meaningless reports 
completely:

https://lore.kernel.org/linux-btrfs/20221103151051.28669-1-dsterba@suse.com/T/

Thanks,
Qu

> 
> [   93.080051][ T8445] Kernel panic - not syncing: panic_on_warn set ...
> [   93.080584][ T8445] CPU: 0 PID: 8445 Comm: a.out Not tainted 6.0.0+ #39
> [   93.081120][ T8445] Hardware name: QEMU Standard PC (i440FX + PIIX,
> 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
> [   93.081919][ T8445] Call Trace:
> [   93.082209][ T8445]  <TASK>
> [   93.082478][ T8445]  dump_stack_lvl+0x1b1/0x28e
> [   93.082897][ T8445]  ? io_alloc_page_table+0xfe/0xfe
> [   93.083340][ T8445]  ? panic+0x81b/0x81b
> [   93.083709][ T8445]  ? _btrfs_ioctl_set_received_subvol+0xbe0/0x1660
> [   93.084260][ T8445]  panic+0x2c2/0x81b
> [   93.084597][ T8445]  ? __warn+0x131/0x220
> [   93.084955][ T8445]  ? asan.module_ctor+0x4/0x4
> [   93.085379][ T8445]  ? _btrfs_ioctl_set_received_subvol+0xc93/0x1660
> [   93.085933][ T8445]  __warn+0x1fc/0x220
> [   93.086282][ T8445]  ? _btrfs_ioctl_set_received_subvol+0xc93/0x1660
> [   93.086744][ T8445]  report_bug+0x1b3/0x2d0
> [   93.087034][ T8445]  handle_bug+0x3d/0x70
> [   93.087345][ T8445]  exc_invalid_op+0x16/0x40
> [   93.087708][ T8445]  asm_exc_invalid_op+0x16/0x20
> [   93.088121][ T8445] RIP: 0010:_btrfs_ioctl_set_received_subvol+0xc93/0x1660
> [   93.088707][ T8445] Code: 76 e6 8a 44 89 fa 31 c0 e8 9f 55 a6 06 4c
> 8b 6c 24 10 eb 18 e8 7e 3a 04 fe 48 c7 c7 20 75 e6 8a 44 89 fe 31 c0
> e8 fd b4 cd fd <0f> 0b 4c 89 ef 48 c7 c6 c0 87 e6 8a ba f6 12 00 00 e9
> a7 06 00 00
> [   93.090000][ T8445] RSP: 0018:ffffc9000280f7a8 EFLAGS: 00010246
> [   93.090524][ T8445] RAX: cceb294c9a36ee00 RBX: ffff88802b27c001
> RCX: ffff88801e0cc880
> [   93.091197][ T8445] RDX: 0000000000000000 RSI: 0000000080000000
> RDI: 0000000000000000
> [   93.091833][ T8445] RBP: 00000000fffffff4 R08: ffffffff816b75fc
> R09: ffffed100c784f14
> [   93.092488][ T8445] R10: ffffed100c784f14 R11: 0000000000000000
> R12: ffff88802c664440
> [   93.093079][ T8445] R13: ffff88802c6643f0 R14: 1ffff110058cc888
> R15: 00000000fffffff4
> [   93.093585][ T8445]  ? __wake_up_klogd+0xcc/0x100
> [   93.094019][ T8445]  ? _btrfs_ioctl_set_received_subvol+0xc93/0x1660
> [   93.094542][ T8445]  btrfs_ioctl+0x1cf0/0x9db0
> [   93.094858][ T8445]  ? btrfs_ioctl_get_supported_features+0x40/0x40
> [   93.095352][ T8445]  ? lockdep_hardirqs_on_prepare+0x428/0x790
> [   93.095870][ T8445]  ? rcu_read_lock_sched_held+0x87/0x110
> [   93.096361][ T8445]  ? __bpf_trace_rcu_stall_warning+0x10/0x10
> [   93.096887][ T8445]  ? lockdep_hardirqs_on_prepare+0x428/0x790
> [   93.097401][ T8445]  ? do_vfs_ioctl+0xc35/0x29e0
> [   93.097853][ T8445]  ? __ia32_compat_sys_ioctl+0xb90/0xb90
> [   93.098321][ T8445]  ? __lock_acquire+0x6080/0x6080
> [   93.098754][ T8445]  ? slab_free_freelist_hook+0x12e/0x1a0
> [   93.099216][ T8445]  ? tomoyo_path_number_perm+0x5be/0x790
> [   93.099668][ T8445]  ? kfree+0xda/0x350
> [   93.100028][ T8445]  ? tomoyo_path_number_perm+0x627/0x790
> [   93.100500][ T8445]  ? tomoyo_check_path_acl+0x1c0/0x1c0
> [   93.100967][ T8445]  ? rcu_read_lock_sched_held+0x87/0x110
> [   93.101502][ T8445]  ? lockdep_hardirqs_on_prepare+0x428/0x790
> [   93.101995][ T8445]  ? print_irqtrace_events+0x220/0x220
> [   93.102327][ T8445]  ? vtime_user_exit+0x2b2/0x3e0
> [   93.102647][ T8445]  ? __ct_user_exit+0xd9/0x160
> [   93.102946][ T8445]  ? bpf_lsm_file_ioctl+0x5/0x10
> [   93.103249][ T8445]  ? security_file_ioctl+0x9d/0xb0
> [   93.103566][ T8445]  ? btrfs_ioctl_get_supported_features+0x40/0x40
> [   93.103953][ T8445]  __se_sys_ioctl+0xfb/0x170
> [   93.104232][ T8445]  do_syscall_64+0x3d/0x90
> [   93.104501][ T8445]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> [   93.104855][ T8445] RIP: 0033:0x7fbfad8e4469
> [   93.105126][ T8445] Code: 00 f3 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 8b 0d ff 49 2b 00 f7 d8
> 64 89 01 48
> [   93.106297][ T8445] RSP: 002b:00007fffb93a1248 EFLAGS: 00000202
> ORIG_RAX: 0000000000000010
> [   93.106853][ T8445] RAX: ffffffffffffffda RBX: 0000000000000000
> RCX: 00007fbfad8e4469
> [   93.107377][ T8445] RDX: 0000000020072c40 RSI: 00000000c0c09425
> RDI: 0000000000000006
> [   93.107901][ T8445] RBP: 00007fffb93a1260 R08: 0000000000000001
> R09: 00007fffb93a1260
> [   93.108441][ T8445] R10: 0000000000000001 R11: 0000000000000202
> R12: 00005650a6c01170
> [   93.108933][ T8445] R13: 00007fffb93a13a0 R14: 0000000000000000
> R15: 0000000000000000
> [   93.109418][ T8445]  </TASK>
> [   93.109843][ T8445] Kernel Offset: disabled
> [   93.110188][ T8445] Rebooting in 86400 seconds..
> 
> Best,
> Wei
> 
> On Tue, 15 Nov 2022 at 18:42, Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:
>>
>>
>>
>> On 2022/11/15 18:30, Wei Chen wrote:
>>> Dear Linux developers,
>>>
>>> I hope the following bug report is helpful.
>>>
>>> Best,
>>> Wei
>>>
>>> On Sun, 13 Nov 2022 at 19:38, Wei Chen <harperchen1110@gmail.com> wrote:
>>>>
>>>> Dear Linux Developer,
>>>>
>>>> Recently when using our tool to fuzz kernel, the following crash was
>>>> triggered. The bug persists in Linux 6.0.
>>>>
>>>> HEAD commit:  4f5365f77018  Linux 5.15.76
>>
>> Not related to the bug itself, but more on the report.
>>
>> I'd say, if the bug persists in the latest release, then please use the
>> latest kernel in the report.
>> Not use the latest LTS as the commit.
>>
>> You know most (if not all) linux communities are working on upstream
>> code, not some LTS branch.
>>
>> Thanks,
>> Qu
>>
>>>> git tree: stable
>>>> compiler: gcc 7.5.0
>>>> console output:
>>>> https://drive.google.com/file/d/1wkzu8jz6edriSP6TpsCGYD5AzkLajIEv/view?usp=share_link
>>>> kernel config: https://drive.google.com/file/d/1flhc33savDkmYN6PRU5C2vXDX0LAKMvM/view?usp=share_link
>>>> C reproducer: https://drive.google.com/file/d/1zKWsWAOcaHfPKewTG6P3pnnVfwH_WXa9/view?usp=share_link
>>>> Syz reproducer:
>>>> https://drive.google.com/file/d/1jUR8_6Re4xpJhyLdXqPiiV72WT-Tk8A-/view?usp=share_link
>>>>
>>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>>> Reported-by: Wei Chen <harperchen1110@gmail.com>
>>>>
>>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
>>>> R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffd3c817900
>>>>    </TASK>
>>>> ------------[ cut here ]------------
>>>> WARNING: CPU: 1 PID: 29222 at fs/btrfs/ioctl.c:4521
>>>> _btrfs_ioctl_set_received_subvol+0x221/0x430 fs/btrfs/ioctl.c:4521
>>>> Modules linked in:
>>>> CPU: 1 PID: 29222 Comm: syz-executor.0 Not tainted 5.15.76 #5
>>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>>>> rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
>>>> RIP: 0010:_btrfs_ioctl_set_received_subvol+0x221/0x430 fs/btrfs/ioctl.c:4521
>>>> Code: e8 74 34 44 ff 83 fb fb 0f 84 de 01 00 00 83 fb e2 0f 84 d5 01
>>>> 00 00 e8 5d 34 44 ff 89 de 48 c7 c7 c0 f8 39 85 e8 9f dc 2e ff <0f> 0b
>>>> e8 48 34 44 ff 89 d9 ba a9 11 00 00 e9 45 01 00 00 49 8b 4f
>>>> RSP: 0018:ffffc9000aecfd40 EFLAGS: 00010286
>>>> RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: ffffc900013ed000
>>>> RDX: 0000000000040000 RSI: ffffffff812d935c RDI: 00000000ffffffff
>>>> RBP: ffffc9000aecfda0 R08: 0000000000000000 R09: 0000000000000001
>>>> R10: ffffc9000aecfbe0 R11: 0000000000000003 R12: ffff888014210400
>>>> R13: ffff8880208d2000 R14: ffff88810c4f21c0 R15: ffff88810f37b600
>>>> FS:  00007f41ffc27700(0000) GS:ffff88813dc00000(0000) knlGS:0000000000000000
>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> CR2: 00007fab915f7008 CR3: 000000002096e000 CR4: 00000000003526e0
>>>> Call Trace:
>>>>    <TASK>
>>>>    btrfs_ioctl_set_received_subvol_32 fs/btrfs/ioctl.c:4584 [inline]
>>>>    btrfs_ioctl+0x2154/0x3d50 fs/btrfs/ioctl.c:5007
>>>>    vfs_ioctl fs/ioctl.c:51 [inline]
>>>>    __do_sys_ioctl fs/ioctl.c:874 [inline]
>>>>    __se_sys_ioctl fs/ioctl.c:860 [inline]
>>>>    __x64_sys_ioctl+0xb6/0x100 fs/ioctl.c:860
>>>>    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>>>>    do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
>>>>    entry_SYSCALL_64_after_hwframe+0x61/0xcb
>>>> RIP: 0033:0x4697f9
>>>> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 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:00007f41ffc26c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>>>> RAX: ffffffffffffffda RBX: 000000000077bf80 RCX: 00000000004697f9
>>>> RDX: 0000000020072c40 RSI: 00000000c0c09425 RDI: 0000000000000005
>>>> RBP: 00007f41ffc26c80 R08: 0000000000000000 R09: 0000000000000000
>>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
>>>> R13: 0000000000000000 R14: 000000000077bf80 R15: 00007ffd3c817900
>>>>    </TASK>
>>>>
>>>> Best,
>>>> Wei