FYI, we noticed the below changes on

https://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next.git pending-ordered-fix
commit 9476e6cfdffdb9d57f22cded973e7a0bf84c7dbe ("Btrfs: use btrfs_get_fs_root in resolve_indirect_ref")


[   18.687436] BTRFS: selftest: Running outstanding_extents tests
[   18.689554] BTRFS: selftest: Running qgroup tests
[   18.690730] BTRFS: selftest: Qgroup basic add
[   18.691901] BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
[   18.693841] IP: [<ffffffff813abbb6>] btrfs_root_node+0x6c/0x1e1
[   18.695275] PGD 0 
[   18.695802] Oops: 0000 [#1] 
[   18.696570] Modules linked in:
[   18.697333] CPU: 0 PID: 1 Comm: swapper Not tainted 4.2.0-rc7-00002-g9476e6c #1
[   18.699048] task: ffff8800780ec040 ti: ffff8800780f0000 task.ti: ffff8800780f0000
[   18.700718] RIP: 0010:[<ffffffff813abbb6>]  [<ffffffff813abbb6>] btrfs_root_node+0x6c/0x1e1
[   18.700718] RSP: 0018:ffff8800780f3a18  EFLAGS: 00010202
[   18.700718] RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000001
[   18.700718] RDX: 0000000000000001 RSI: ffffffff81c393a0 RDI: 0000000000000246
[   18.700718] RBP: ffff8800780f3a38 R08: 0000000000000000 R09: 000000000000036c
[   18.700718] R10: 0000000000000000 R11: 0000000000000001 R12: ffff880053404000
[   18.700718] R13: 0000000000000000 R14: ffff8800780f3c10 R15: ffff880054409670
[   18.700718] FS:  0000000000000000(0000) GS:ffffffff81c21000(0000) knlGS:0000000000000000
[   18.700718] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   18.700718] CR2: 0000000000000058 CR3: 000000007f9f0000 CR4: 00000000000406b0
[   18.700718] Stack:
[   18.700718]  ffffffff813abb63 0000000000000292 0000000000000002 ffff880053404000
[   18.700718]  ffff8800780f3a68 ffffffff813ad0e3 ffff88005eb58a10 0000000000000002
[   18.700718]  ffff88005eb58a10 ffff880054409670 ffff8800780f3b78 ffffffff81444470
[   18.700718] Call Trace:
[   18.700718]  [<ffffffff813abb63>] ? btrfs_root_node+0x19/0x1e1
[   18.700718]  [<ffffffff813ad0e3>] btrfs_old_root_level+0x1d/0xb7
[   18.700718]  [<ffffffff81444470>] __resolve_indirect_refs+0x3ab/0x9c7
[   18.700718]  [<ffffffff814441ab>] ? __resolve_indirect_refs+0xe6/0x9c7
[   18.700718]  [<ffffffff817a95c6>] ? _raw_read_lock+0x42/0x49
[   18.700718]  [<ffffffff81419afc>] ? btrfs_tree_read_unlock+0x5a/0x80
[   18.700718]  [<ffffffff8108cf8c>] ? do_raw_read_unlock+0x5/0x20
[   18.700718]  [<ffffffff817a9704>] ? _raw_read_unlock+0x2b/0x38
[   18.700718]  [<ffffffff81445165>] find_parent_nodes+0x66c/0x1361
[   18.700718]  [<ffffffff81445f19>] __btrfs_find_all_roots+0xbf/0x11d
[   18.700718]  [<ffffffff81445fab>] btrfs_find_all_roots+0x18/0x65
[   18.700718]  [<ffffffff81464f1b>] test_no_shared_qgroup+0xec/0x290
[   18.700718]  [<ffffffff81d41354>] ? trace_event_define_fields_btrfs_space_reservation+0xf7/0xf7
[   18.700718]  [<ffffffff814652aa>] btrfs_test_qgroups+0x1eb/0x261
[   18.700718]  [<ffffffff81d41468>] init_btrfs_fs+0x114/0x17a
[   18.700718]  [<ffffffff810002ca>] do_one_initcall+0xb2/0x1c8
[   18.700718]  [<ffffffff81d1011b>] kernel_init_freeable+0x116/0x1a2
[   18.700718]  [<ffffffff8179ac26>] ? rest_init+0x136/0x136
[   18.700718]  [<ffffffff8179ac34>] kernel_init+0xe/0xdc
[   18.700718]  [<ffffffff817aa08f>] ret_from_fork+0x3f/0x70
[   18.700718]  [<ffffffff8179ac26>] ? rest_init+0x136/0x136
[   18.700718] Code: 85 c0 74 0d 80 3d 33 19 94 00 00 0f 84 8c 00 00 00 49 8b 1c 24 e8 3b 6f cf ff 85 c0 74 0d 80 3d 1a 19 94 00 00 0f 84 a4 00 00 00 <8b> 4b 58 85 c9 0f 84 d0 00 00 00 8d 71 01 48 8d 7b 58 89 c8 0f 
[   18.700718] RIP  [<ffffffff813abbb6>] btrfs_root_node+0x6c/0x1e1
[   18.700718]  RSP <ffff8800780f3a18>
[   18.700718] CR2: 0000000000000058
[   18.700718] ---[ end trace d6dc5dcc9f64a4ec ]---
[   18.700718] Kernel panic - not syncing: Fatal exception


To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Ying Huang