XFS memory allocation deadlock

[Bill Maidment]

Hi friends
I have run into a problem in SL7.6 copying a large KVM guest lvm 
snapshot file using cp --sparse=always
I get flooded with the following message:
XFS: cp(12985) possible memory allocation deadlock size 131088 in 
kmem_realloc (mode:0x250)

The copy ends eventually, but it takes much longer than I expected.
Has anyone else come across this? Googling doesn't throw much light on 
this.

--
Cheers
Bill