mm/mm_init.c: extend init unavailable range doc info

Besides of the already described reasons the pages backended memory holes
might be persistent due to having memory mapped IO spaces behind those
ranges in the framework of flatmem kernel config.  Add such note to the
init_unavailable_range() method kdoc in order to point out to one more
reason of having the function executed for such regions.

[fancer.lancer@gmail.com: update per Mike]
Link: https://lkml.kernel.org/r/20231202111855.18392-1-fancer.lancer@gmail.com
Link: https://lkml.kernel.org/r/20231122182419.30633-6-fancer.lancer@gmail.com
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 077bfe393b5e29e73e98d4071385f7cc3c5c4cc6..824bf53e825317741be9eb2784da73aaca864421 100644 (file)
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -796,6 +796,7 @@ overlap_memmap_init(unsigned long zone, unsigned long *pfn)
  * - physical memory bank size is not necessarily the exact multiple of the
  *   arbitrary section size
  * - early reserved memory may not be listed in memblock.memory
+ * - non-memory regions covered by the contigious flatmem mapping
  * - memory layouts defined with memmap= kernel parameter may not align
  *   nicely with memmap sections
  *