Low memory deadlock with md devices

Issue

• Low memory deadlock with md devices:

PID: 48786  TASK: ffff9f58249cc200  CPU: 24  COMMAND: "TaniumClient"
 #0 [ffff9f54cbc57260] __schedule at ffffffffbcb88dc8
 #1 [ffff9f54cbc572c8] schedule at ffffffffbcb89199
 #2 [ffff9f54cbc572d8] schedule_timeout at ffffffffbcb86e61
 #3 [ffff9f54cbc57380] io_schedule_timeout at ffffffffbcb88a4d
 #4 [ffff9f54cbc573b0] io_schedule at ffffffffbcb88ae8
 #5 [ffff9f54cbc573c0] __xfs_iunpin_wait at ffffffffc03d7a51 [xfs]
 #6 [ffff9f54cbc57438] xfs_iunpin_wait at ffffffffc03da569 [xfs]
 #7 [ffff9f54cbc57448] xfs_reclaim_inode at ffffffffc03ce5c3 [xfs]
 #8 [ffff9f54cbc57498] xfs_reclaim_inodes_ag at ffffffffc03cea47 [xfs]
 #9 [ffff9f54cbc57630] xfs_reclaim_inodes_nr at ffffffffc03cfaf3 [xfs]
#10 [ffff9f54cbc57650] xfs_fs_free_cached_objects at ffffffffc03e00a5 [xfs]
#11 [ffff9f54cbc57660] prune_super at ffffffffbc651099
#12 [ffff9f54cbc57690] shrink_slab at ffffffffbc5d2435
#13 [ffff9f54cbc57738] do_try_to_free_pages at ffffffffbc5d571a
#14 [ffff9f54cbc577b0] try_to_free_pages at ffffffffbc5d596c
#15 [ffff9f54cbc57848] __alloc_pages_nodemask at ffffffffbc5c9591
#16 [ffff9f54cbc57978] alloc_pages_current at ffffffffbc619388
#17 [ffff9f54cbc579c0] new_slab at ffffffffbc627a73
#18 [ffff9f54cbc57a00] ___slab_alloc at ffffffffbc627f8c
#19 [ffff9f54cbc57ad8] __slab_alloc at ffffffffbcb7fe85
#20 [ffff9f54cbc57b18] kmem_cache_alloc at ffffffffbc62914b
#21 [ffff9f54cbc57b58] alloc_inode at ffffffffbc66b881
#22 [ffff9f54cbc57b78] iget_locked at ffffffffbc66d0bc
#23 [ffff9f54cbc57bb8] kernfs_get_inode at ffffffffbc6d86e7
#24 [ffff9f54cbc57bd8] kernfs_iop_lookup at ffffffffbc6d940b
#25 [ffff9f54cbc57c00] lookup_real at ffffffffbc659183
....

PID: 1169   TASK: ffff9f505fde4200  CPU: 7   COMMAND: "md127_raid1"
 #0 [ffff9f505add3ba0] __schedule at ffffffffbcb88dc8
 #1 [ffff9f505add3c08] schedule_preempt_disabled at ffffffffbcb8a0b9
 #2 [ffff9f505add3c18] __mutex_lock_slowpath at ffffffffbcb88207
 #3 [ffff9f505add3c70] mutex_lock at ffffffffbcb875df
 #4 [ffff9f505add3c88] kernfs_find_and_get_ns at ffffffffbc6d9363
 #5 [ffff9f505add3cb0] sysfs_notify at ffffffffbc6dbb3b
 #6 [ffff9f505add3cd8] md_update_sb at ffffffffbc9adbe4
 #7 [ffff9f505add3d58] md_check_recovery at ffffffffbc9ae8da
 #8 [ffff9f505add3d78] raid1d at ffffffffc011f661 [raid1]
 #9 [ffff9f505add3e50] md_thread at ffffffffbc9a5f0d
#10 [ffff9f505add3ec8] kthread at ffffffffbc4c5e41