This doesn't work if the underlying slab allocator doesn't define
__kmalloc_node_track_caller() regardless of whether CONFIG_TRACING is
enabled or not. SLOB, for example, never defines it, and that's why the
conditional exists in the way it currently does.
This is your patch with CONFIG_EMBEDDED && CONFIG_SLOB:
mm/built-in.o: In function `__krealloc':
(.text+0x1283c): undefined reference to `__kmalloc_track_caller'
mm/built-in.o: In function `kmemdup':
(.text+0x128b4): undefined reference to `__kmalloc_track_caller'
mm/built-in.o: In function `kstrndup':
(.text+0x128fc): undefined reference to `__kmalloc_track_caller'
mm/built-in.o: In function `kstrdup':
(.text+0x12943): undefined reference to `__kmalloc_track_caller'
mm/built-in.o: In function `memdup_user':
(.text+0x129f7): undefined reference to `__kmalloc_track_caller'
drivers/built-in.o:(.text+0xc48a4): more undefined references to `__kmalloc_track_caller' follow
net/built-in.o: In function `__alloc_skb':
(.text+0x8dc6): undefined reference to `__kmalloc_node_track_caller'
--
