RHEL8: 内节点删除和块分配之间的 xfs_buf 死锁

Issue

• 任务被阻塞，日志如下：

[6553607.856923] INFO: task irisdb:1499256 blocked for more than 120 seconds.
[6553607.856958]       Tainted: G           OE    --------- -  - 4.18.0-372.9.1.el8.x86_64 #1
[6553607.856980] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[6553607.857001] task:irisdb          state:D stack:    0 pid:1499256 ppid:     1 flags:0x10004080
[6553607.857004] Call Trace:
[6553607.857007]  __schedule+0x2d1/0x830
[6553607.857016]  schedule+0x35/0xa0
[6553607.857018]  schedule_timeout+0x274/0x300
[6553607.857023]  ? dma_map_sg_attrs+0x30/0x50
[6553607.857027]  ? scsi_dma_map+0x35/0x40
[6553607.857033]  __down+0x9a/0xf0
[6553607.857037]  ? sd_init_command+0x1e9/0xc80 [sd_mod]
[6553607.857042]  ? xfs_buf_find.isra.29+0x3c8/0x5f0 [xfs]
[6553607.857104]  down+0x3b/0x50
[6553607.857108]  xfs_buf_lock+0x33/0xf0 [xfs]
[6553607.857147]  xfs_buf_find.isra.29+0x3c8/0x5f0 [xfs]
[6553607.857189]  xfs_buf_get_map+0x4c/0x320 [xfs]
[6553607.857230]  xfs_buf_read_map+0x53/0x310 [xfs]
[6553607.857267]  ? xfs_read_agf+0x8e/0x120 [xfs]
[6553607.857295]  xfs_trans_read_buf_map+0x1cb/0x360 [xfs]
[6553607.857343]  ? xfs_read_agf+0x8e/0x120 [xfs]
[6553607.857371]  xfs_read_agf+0x8e/0x120 [xfs]
[6553607.857399]  xfs_alloc_read_agf+0x3e/0x1e0 [xfs]
[6553607.857427]  xfs_alloc_fix_freelist+0x234/0x480 [xfs]
[6553607.857455]  ? up+0x12/0x50
[6553607.857457]  ? xfs_buf_rele+0x57/0x370 [xfs]
[6553607.857494]  xfs_free_extent_fix_freelist+0x64/0xb0 [xfs]
[6553607.857523]  __xfs_free_extent+0x58/0x170 [xfs]
[6553607.857583]  ? xfs_defer_finish_noroll+0xb1/0x5d0 [xfs]
[6553607.857614]  xfs_trans_free_extent+0x46/0x110 [xfs]
[6553607.857694]  xfs_extent_free_finish_item+0x23/0x40 [xfs]
[6553607.857734]  xfs_defer_finish_noroll+0x1f6/0x5d0 [xfs]
[6553607.857768]  xfs_defer_finish+0x13/0x70 [xfs]
[6553607.857800]  xfs_itruncate_extents_flags+0xc6/0x240 [xfs]
[6553607.857841]  xfs_inactive_truncate+0xa3/0xf0 [xfs]
[6553607.857880]  xfs_inactive+0x15a/0x170 [xfs]
[6553607.857918]  xfs_fs_destroy_inode+0xa8/0x1c0 [xfs]
[6553607.857958]  do_unlinkat+0x250/0x2e0
[6553607.857965]  do_syscall_64+0x5b/0x1a0
[6553607.857970]  entry_SYSCALL_64_after_hwframe+0x65/0xca
[6553607.857973] RIP: 0033:0x7fab3945e60b
[6553607.857978] Code: Unable to access opcode bytes at RIP 0x7fab3945e5e1.
[6553607.857979] RSP: 002b:00007ffeb1429a58 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
[6553607.857981] RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007fab3945e60b
[6553607.857982] RDX: 00007ffeb1429a95 RSI: 00007ffeb1428e8a RDI: 00007ffeb1429a60
[6553607.857983] RBP: 00007fab3b0c2690 R08: 00007ffeb1428e14 R09: 0000000000000000
[6553607.857985] R10: ff00ff00ff00ff00 R11: 0000000000000246 R12: 0000000000000034
[6553607.857986] R13: 0000000000000068 R14: ffffffffffffffff R15: 0000000000000003