mm: mmap: map MAP_STACK to VM_NOHUGEPAGE only if THP is enabled

commit c4608d1 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE") maps the
mmap option MAP_STACK to VM_NOHUGEPAGE.  This is also done if
CONFIG_TRANSPARENT_HUGEPAGE is not defined.  But in that case, the
VM_NOHUGEPAGE does not make sense.

I discovered this issue when trying to use the tool CRIU to checkpoint and
restore a container.  Our running kernel is compiled without
CONFIG_TRANSPARENT_HUGEPAGE.  CRIU parses the output of /proc/<pid>/smaps
and saves the "nh" flag.  When trying to restore the container, CRIU fails
to restore the "nh" mappings, since madvise() MADV_NOHUGEPAGE always
returns an error because CONFIG_TRANSPARENT_HUGEPAGE is not defined.

Link: https://lkml.kernel.org/r/20250507-map-map_stack-to-vm_nohugepage-only-if-thp-is-enabled-v5-1-c6c38cfefd6e@kuka.com
Fixes: c4608d1 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE")
Signed-off-by: Ignacio Moreno Gonzalez <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: specht478

include/linux/mman.h

@@ -155,7 +155,9 @@ calc_vm_flag_bits(struct file *file, unsigned long flags)
 	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
 	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
 	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      ) |
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	       _calc_vm_trans(flags, MAP_STACK,	     VM_NOHUGEPAGE) |
+#endif
 	       arch_calc_vm_flag_bits(file, flags);
 }