[PATCH 3/3] mm: SKIP KASAN for page table allocations

[Muhammad Usama Anjum]

Page tables are always accessed via __va(phys) / phys_to_virt(phys).
With a match-all tag in the pointer, MTE never checks memory tags on
access. Therefore: KASAN HW tags are set during page table allocation
but never checked during use. KASAN poisoning on free provides no
value for these pages as well. Its pure overhead - both at allocation
time and free time. Hence, skip the tag setting for all page tables.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@xxxxxxx>
---
 include/asm-generic/pgalloc.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 57137d3ac1592..051aa1331051c 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -4,7 +4,7 @@
 
 #ifdef CONFIG_MMU
 
-#define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO)
+#define GFP_PGTABLE_KERNEL	(GFP_KERNEL | __GFP_ZERO | __GFP_SKIP_KASAN)
 #define GFP_PGTABLE_USER	(GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
 
 /**
-- 
2.47.3