[PATCH v2 0/8] treewide: remove unnecessary invalid range checks in memblock iteration loops

[PATCH v2 0/8] treewide: remove unnecessary invalid range checks in memblock iteration loops

[Sang-Heon Jeon]

The memblock API guarantees that for_each_mem_range() and
for_each_mem_pfn_range() never return an invalid range, meaning start is
always less than end.

Several memblock callers still have unnecessary invalid range checks in
their loop bodies, so remove them.

Patches 1-6 cover for_each_mem_range() callers. memblock never stores a
zero-size region, so the range it returns always has start < end. Some
callers apply __va() or __phys_to_virt() before comparing, but these keep
start < end too, so the check is unreachable.

Patches 7-8 cover for_each_mem_pfn_range() callers. __next_mem_pfn_range()
skips any region that contains no whole page, so it only ever returns
start_pfn < end_pfn and the check is unnecessary.

For reference, commit 36ca7f4be809 ("arm64: mm: Remove bogus stop
condition from map_mem() loop") did a similar cleanup in arm64 map_mem().

All these checks are in different trees, so I split the change into one
patch per arch/subsystem. The patches are independent and can be applied
separately.

---
Changes from v1 [1]
- Add review-by, tested-by tags from v1
- Add missing simliar patches(5,6) to patch series
- Change base to rppt/for-next

[1] https://lore.kernel.org/all/20260621145919.1453-1-ekffu200098@gmail.com/
---

Sang-Heon Jeon (8):
  arm64: mm: remove unreachable invalid range check in
    kasan_init_shadow()
  LoongArch: remove unreachable invalid range check in kasan_init()
  riscv: remove unreachable invalid range check in
    create_linear_mapping_page_table()
  riscv: remove unreachable invalid range check in kasan_init()
  ARM: remove unreachable invalid range check in kasan_init()
  powerpc64/kasan: Remove unreachable invalid range check in
    kasan_init_phys_region()
  mm: remove unnecessary empty range check in
    early_calculate_totalpages()
  mm/hugetlb: remove unnecessary empty range check in
    hugetlb_bootmem_set_nodes()

 arch/arm/mm/kasan_init.c               | 6 ------
 arch/arm64/mm/kasan_init.c             | 3 ---
 arch/loongarch/mm/kasan_init.c         | 3 ---
 arch/powerpc/mm/kasan/init_book3e_64.c | 3 ---
 arch/powerpc/mm/kasan/init_book3s_64.c | 3 ---
 arch/riscv/mm/init.c                   | 2 --
 arch/riscv/mm/kasan_init.c             | 3 ---
 mm/hugetlb.c                           | 3 +--
 mm/mm_init.c                           | 3 +--
 9 files changed, 2 insertions(+), 27 deletions(-)

-- 
2.43.0

[PATCH v2 6/8] powerpc64/kasan: Remove unreachable invalid range check in kasan_init_phys_region()

[Sang-Heon Jeon]

kasan_init() maps each memblock region with for_each_mem_range() and passes
it to kasan_init_phys_region(), which does nothing when start >= end.
for_each_mem_range() never returns an invalid range, so start < end always.

Therefore the start >= end check is unreachable, so remove it.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 arch/powerpc/mm/kasan/init_book3e_64.c | 3 ---
 arch/powerpc/mm/kasan/init_book3s_64.c | 3 ---
 2 files changed, 6 deletions(-)

diff --git a/arch/powerpc/mm/kasan/init_book3e_64.c b/arch/powerpc/mm/kasan/init_book3e_64.c
index 0d3a73d6d4b0..0ed372fb8b09 100644
--- a/arch/powerpc/mm/kasan/init_book3e_64.c
+++ b/arch/powerpc/mm/kasan/init_book3e_64.c
@@ -68,9 +68,6 @@ static void __init kasan_init_phys_region(void *start, void *end)
 	unsigned long k_start, k_end, k_cur;
 	void *va;
 
-	if (start >= end)
-		return;
-
 	k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
 	k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
 
diff --git a/arch/powerpc/mm/kasan/init_book3s_64.c b/arch/powerpc/mm/kasan/init_book3s_64.c
index dcafa641804c..ccfbfb894637 100644
--- a/arch/powerpc/mm/kasan/init_book3s_64.c
+++ b/arch/powerpc/mm/kasan/init_book3s_64.c
@@ -24,9 +24,6 @@ static void __init kasan_init_phys_region(void *start, void *end)
 	unsigned long k_start, k_end, k_cur;
 	void *va;
 
-	if (start >= end)
-		return;
-
 	k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
 	k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
 
-- 
2.43.0