[018/227] mm/memremap: avoid calling kasan_remove_zero_shadow() for device private memory

Commit Message

Andrew Morton March 22, 2022, 9:39 p.m. UTC

From: Miaohe Lin <[e-mail]>
Subject: mm/memremap: avoid calling kasan_remove_zero_shadow() for device private memory

For device private memory, we do not create a linear mapping for the
memory because the device memory is un-accessible.  Thus we do not add
kasan zero shadow for it.  So it's unnecessary to do
kasan_remove_zero_shadow() for it.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Reviewed-by: Muchun Song <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memremap.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Patch

--- a/mm/memremap.c~mm-memremap-avoid-calling-kasan_remove_zero_shadow-for-device-private-memory
+++ a/mm/memremap.c
@@ -282,7 +282,8 @@  static int pagemap_range(struct dev_page
 	return 0;
 
 err_add_memory:
-	kasan_remove_zero_shadow(__va(range->start), range_len(range));
+	if (!is_private)
+		kasan_remove_zero_shadow(__va(range->start), range_len(range));
 err_kasan:
 	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
 err_pfn_remap: