init/main.c: add warning when file specified in rdinit is inaccessible

Avoid silently ignoring the initramfs when the file specified in rdinit is
not usable.  This prints an error that clearly explains the issue (file
was not found, vs initramfs was not found).

Link: https://lkml.kernel.org/r/20250707091411.1412681-1-lillian@star-ark.net
Signed-off-by: Lillian Berry <lillian@star-ark.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Lillian Berry

init/main.c

@@ -1592,7 +1592,11 @@ static noinline void __init kernel_init_freeable(void)
 	 * check if there is an early userspace init.  If yes, let it do all
 	 * the work
 	 */
-	if (init_eaccess(ramdisk_execute_command) != 0) {
+	int ramdisk_command_access;
+	ramdisk_command_access = init_eaccess(ramdisk_execute_command);
+	if (ramdisk_command_access != 0) {
+		pr_warn("check access for rdinit=%s failed: %i, ignoring\n",
+			ramdisk_execute_command, ramdisk_command_access);
 		ramdisk_execute_command = NULL;
 		prepare_namespace();
 	}