arch/s390: teach arch_get_unmapped_area{_topdown} to handle hugetlb mappings

We want to stop special casing hugetlb mappings and make them go through
generic channels, so teach arch_get_unmapped_area{_topdown} to handle
those.

s390 specific hugetlb function does not set info.align_offset, so do the
same here for compatibility.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Oscar Salvador <[e-mail]>
Cc: David Hildenbrand <[e-mail]>
Cc: Donet Tom <[e-mail]>
Cc: Lorenzo Stoakes <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Muchun Song <[e-mail]>
Cc: Peter Xu <[e-mail]>
Cc: Vlastimil Babka <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/s390/mm/mmap.c

···
 #include <linux/random.h>
 #include <linux/compat.h>
 #include <linux/security.h>
+#include <linux/hugetlb.h>
 #include <asm/elf.h>
 
 static unsigned long stack_maxrandom_size(void)
···
 
 static int get_align_mask(struct file *filp, unsigned long flags)
 {
+	if (filp && is_file_hugepages(filp))
+		return huge_page_mask_align(filp);
 	if (!(current->flags & PF_RANDOMIZE))
 		return 0;
 	if (filp || (flags & MAP_SHARED))
···
 	info.low_limit = mm->mmap_base;
 	info.high_limit = TASK_SIZE;
 	info.align_mask = get_align_mask(filp, flags);
-	info.align_offset = pgoff << PAGE_SHIFT;
+	if (!(filp && is_file_hugepages(filp)))
+		info.align_offset = pgoff << PAGE_SHIFT;
 	addr = vm_unmapped_area(&info);
 	if (offset_in_page(addr))
 		return addr;
···
 	info.low_limit = PAGE_SIZE;
 	info.high_limit = mm->mmap_base;
 	info.align_mask = get_align_mask(filp, flags);
-	info.align_offset = pgoff << PAGE_SHIFT;
+	if (!(filp && is_file_hugepages(filp)))
+		info.align_offset = pgoff << PAGE_SHIFT;
 	addr = vm_unmapped_area(&info);
 
 	/*