From: Vasily Gorbik <gor@linux.ibm.com>
Date: Tue, 10 Dec 2024 10:18:32 +0000 (+0100)
Subject: s390/boot: Allow KASAN mapping to fallback to small pages
X-Git-Tag: v6.14-rc1~36^2~49
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=490a5e99ead57b16045a8e968fd8bc5fdcbfc90c;p=thirdparty%2Fkernel%2Flinux.git

s390/boot: Allow KASAN mapping to fallback to small pages

For KASAN shadow mappings, switch from physmem_alloc_or_die() to
physmem_alloc() and return INVALID_PHYS_ADDR on allocation failure. This
allows gracefully falling back from large pages to smaller pages (1MB
or 4KB) if the allocation of 2GB size/aligned pages cannot be fulfilled.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---

diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c
index 3e69e4405d70b..47011b5a9e3d2 100644
--- a/arch/s390/boot/vmem.c
+++ b/arch/s390/boot/vmem.c
@@ -247,9 +247,13 @@ static unsigned long resolve_pa_may_alloc(unsigned long addr, unsigned long size
 		return __identity_pa(addr);
 #ifdef CONFIG_KASAN
 	case POPULATE_KASAN_MAP_SHADOW:
-		addr = physmem_alloc_or_die(RR_VMEM, size, size);
-		memset((void *)addr, 0, size);
-		return addr;
+		/* Allow to fail large page allocations, this will fall back to 1mb/4k pages */
+		addr = physmem_alloc(RR_VMEM, size, size, size == PAGE_SIZE);
+		if (addr) {
+			memset((void *)addr, 0, size);
+			return addr;
+		}
+		return INVALID_PHYS_ADDR;
 #endif
 	default:
 		return INVALID_PHYS_ADDR;