Re: [PATCH] mremap: add MREMAP_NOHOLE flag --resend

jemalloc doesn't really use free lists or sbrk for user allocations much
at all: thread caches are arrays of pointers (easier to flush and no
need to deref stale memory), red-black trees manage chunks and runs
within chunks, and runs use bitmaps. It can use sbrk as an alternate
source of chunks, but it defaults to using mmap and there's no real
advantage to switching it.

THP currently seems to be designed around the assumption that all
userspace allocators are variants of dlmalloc...