mysterious allocations of type `Profile.Allocs.BufferType`

[matthias314]

Sometimes allocations of type Profile.Allocs.BufferType show up:

julia> using AllocationViewer, Random

julia> @track_allocs sort!(randperm(252))
     8 allocs: 4328 bytes at 2 source locations
      5 allocs: 4232 bytes at @Base/boot.jl:588 GenericMemory
 > +   2016 bytes for Profile.Allocs.BufferType
   +   24 bytes for Memory{Int64}
   +   2016 bytes for Profile.Allocs.BufferType
   +   24 bytes for Memory{Int64}
   +   152 bytes for Memory{Int64}
   +  3 allocs: 96 bytes at @Base/boot.jl:648 Array

What do they mean?