[PATCH v2 1/3] fs: stable_page_flags(): use BIT_ULL() for KPF flags

[Jinjiang Tu <tujinjiang@huawei.com>]

The stable_page_flags() function currently sets page flag bits using
"1 << KPF_xxx" for various KPF_* definitions. KPF_* may be larger than 32,
which will trigger -Wshift-count-overflow warning. All KPF_* values
currently used in "1 << KPF_xxx" are smaller than 33, so no warning is
triggered with current code.

Replace all occurrences of "1 << KPF_*" with the BIT_ULL() macro to
ensure all shifts are performed on a 64-bit unsigned type. This makes
the code robust, and safe for future extension.

No functional change is intended.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
---
 fs/proc/page.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 7d9387143435..ee39b321f1c6 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -157,7 +157,7 @@ u64 stable_page_flags(const struct page *page)
 	 * it differentiates a memory hole from a page with no flags
 	 */
 	if (!page)
-		return 1 << KPF_NOPAGE;
+		return BIT_ULL(KPF_NOPAGE);
 
 	snapshot_page(&ps, page);
 	folio = &ps.folio_snapshot;
@@ -170,11 +170,11 @@ u64 stable_page_flags(const struct page *page)
 	 * pseudo flags for the well known (anonymous) memory mapped pages
 	 */
 	if (folio_mapped(folio))
-		u |= 1 << KPF_MMAP;
+		u |= BIT_ULL(KPF_MMAP);
 	if (is_anon) {
-		u |= 1 << KPF_ANON;
+		u |= BIT_ULL(KPF_ANON);
 		if ((mapping & FOLIO_MAPPING_FLAGS) == FOLIO_MAPPING_KSM)
-			u |= 1 << KPF_KSM;
+			u |= BIT_ULL(KPF_KSM);
 	}
 
 	/*
@@ -184,35 +184,35 @@ u64 stable_page_flags(const struct page *page)
 	if (ps.idx == 0)
 		u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
 	else
-		u |= 1 << KPF_COMPOUND_TAIL;
+		u |= BIT_ULL(KPF_COMPOUND_TAIL);
 	if (folio_test_hugetlb(folio))
-		u |= 1 << KPF_HUGE;
+		u |= BIT_ULL(KPF_HUGE);
 	else if (folio_test_large(folio) &&
 	         folio_test_large_rmappable(folio)) {
 		/* Note: we indicate any THPs here, not just PMD-sized ones */
-		u |= 1 << KPF_THP;
+		u |= BIT_ULL(KPF_THP);
 	} else if (is_huge_zero_pfn(ps.pfn)) {
-		u |= 1 << KPF_ZERO_PAGE;
-		u |= 1 << KPF_THP;
+		u |= BIT_ULL(KPF_ZERO_PAGE);
+		u |= BIT_ULL(KPF_THP);
 	} else if (is_zero_pfn(ps.pfn)) {
-		u |= 1 << KPF_ZERO_PAGE;
+		u |= BIT_ULL(KPF_ZERO_PAGE);
 	}
 
 	if (ps.flags & PAGE_SNAPSHOT_PG_BUDDY)
-		u |= 1 << KPF_BUDDY;
+		u |= BIT_ULL(KPF_BUDDY);
 
 	if (folio_test_offline(folio))
-		u |= 1 << KPF_OFFLINE;
+		u |= BIT_ULL(KPF_OFFLINE);
 	if (folio_test_pgtable(folio))
-		u |= 1 << KPF_PGTABLE;
+		u |= BIT_ULL(KPF_PGTABLE);
 	if (folio_test_slab(folio))
-		u |= 1 << KPF_SLAB;
+		u |= BIT_ULL(KPF_SLAB);
 
 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 	u |= kpf_copy_bit(k, KPF_IDLE,          PG_idle);
 #else
 	if (ps.flags & PAGE_SNAPSHOT_PG_IDLE)
-		u |= 1 << KPF_IDLE;
+		u |= BIT_ULL(KPF_IDLE);
 #endif
 
 	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
@@ -227,14 +227,14 @@ u64 stable_page_flags(const struct page *page)
 
 #define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache))
 	if ((k & SWAPCACHE) == SWAPCACHE)
-		u |= 1 << KPF_SWAPCACHE;
+		u |= BIT_ULL(KPF_SWAPCACHE);
 	u |= kpf_copy_bit(k, KPF_SWAPBACKED,	PG_swapbacked);
 
 	u |= kpf_copy_bit(k, KPF_UNEVICTABLE,	PG_unevictable);
 	u |= kpf_copy_bit(k, KPF_MLOCKED,	PG_mlocked);
 
 #ifdef CONFIG_MEMORY_FAILURE
-	if (u & (1 << KPF_HUGE))
+	if (u & BIT_ULL(KPF_HUGE))
 		u |= kpf_copy_bit(k, KPF_HWPOISON,	PG_hwpoison);
 	else
 		u |= kpf_copy_bit(ps.page_snapshot.flags.f, KPF_HWPOISON, PG_hwpoison);
-- 
2.43.0