# \[PATCH v2 3/4\] powerpc/64s: Allow double call of kernel\_\[un\]map\_linear\_page()

- From: Christophe Leroy \<hidden\>
- Date: 2021-03-04 14:36:55 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2021/03/6288369
- Thread: https://ratatoskr.run/linuxppc-dev/2021/03/6288370/t.md

```text
If the page is already mapped resp. already unmapped, bail out.

Signed-off-by: Christophe Leroy <redacted>
---
v2: New
---
 arch/powerpc/mm/book3s64/hash_utils.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index f1b5a5f1d3a9..cb09a49be798 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1944,6 +1944,9 @@ static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
 	if (!vsid)
 		return;
 
+	if (linear_map_hash_slots[lmi] & 0x80)
+		return;
+
 	ret = hpte_insert_repeating(hash, vpn, __pa(vaddr), mode,
 				    HPTE_V_BOLTED,
 				    mmu_linear_psize, mmu_kernel_ssize);
@@ -1963,7 +1966,10 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
 
 	hash = hpt_hash(vpn, PAGE_SHIFT, mmu_kernel_ssize);
 	spin_lock(&linear_map_hash_lock);
-	BUG_ON(!(linear_map_hash_slots[lmi] & 0x80));
+	if (!(linear_map_hash_slots[lmi] & 0x80)) {
+		spin_unlock(&linear_map_hash_lock);
+		return;
+	}
 	hidx = linear_map_hash_slots[lmi] & 0x7f;
 	linear_map_hash_slots[lmi] = 0;
 	spin_unlock(&linear_map_hash_lock);
-- 
2.25.0

```