mm/mm_init: use for_each_valid_pfn() in init_unavailable_range()

Currently, memmap_init initializes pfn_hole with 0 instead of
ARCH_PFN_OFFSET. Then init_unavailable_range will start iterating each
page from the page at address zero to the first available page, but it
won't do anything for pages below ARCH_PFN_OFFSET because pfn_valid
won't pass.

If ARCH_PFN_OFFSET is very large (e.g., something like 2^64-2GiB if the
kernel is used as a library and loaded at a very high address), the
pointless iteration for pages below ARCH_PFN_OFFSET will take a very long
time, and the kernel will look stuck at boot time.

Use for_each_valid_pfn() to skip the pointless iterations.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Woodhouse <[email protected]>
Reported-by: Ruihan Li <[email protected]>
Suggested-by: Mike Rapoport <[email protected]>
Reviewed-by: Mike Rapoport (Microsoft) <[email protected]>
Tested-by: Ruihan Li <[email protected]>
Tested-by: Lorenzo Stoakes <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Marc Rutland <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 1 insertions, 5 deletions

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 7191703a5820..1c5444e188f8 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -851,11 +851,7 @@ static void __init init_unavailable_range(unsigned long spfn,
 	unsigned long pfn;
 	u64 pgcnt = 0;
 
-	for (pfn = spfn; pfn < epfn; pfn++) {
-		if (!pfn_valid(pageblock_start_pfn(pfn))) {
-			pfn = pageblock_end_pfn(pfn) - 1;
-			continue;
-		}
+	for_each_valid_pfn(pfn, spfn, epfn) {
 		__init_single_page(pfn_to_page(pfn), pfn, zone, node);
 		__SetPageReserved(pfn_to_page(pfn));
 		pgcnt++;