+ mm-introduce-clear_highpage_kasan_tagged.patch added to mm-unstable branch

+ mm-introduce-clear_highpage_kasan_tagged.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: introduce clear_highpage_kasan_tagged
has been added to the -mm mm-unstable branch.  Its filename is
     mm-introduce-clear_highpage_kasan_tagged.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-introduce-clear_highpage_kasan_tagged.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Andrey Konovalov <andreyknvl@google.com>
Subject: mm: introduce clear_highpage_kasan_tagged
Date: Thu, 9 Jun 2022 20:18:46 +0200

Add a clear_highpage_kasan_tagged() helper that does clear_highpage() on a
page potentially tagged by KASAN.

This helper is used by the following patch.

Link: https://lkml.kernel.org/r/4471979b46b2c487787ddcd08b9dc5fedd1b6ffd.1654798516.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/highmem.h |   10 ++++++++++
 mm/page_alloc.c         |    8 ++------
 2 files changed, 12 insertions(+), 6 deletions(-)

--- a/include/linux/highmem.h~mm-introduce-clear_highpage_kasan_tagged
+++ a/include/linux/highmem.h
@@ -243,6 +243,16 @@ static inline void clear_highpage(struct
 	kunmap_local(kaddr);
 }
 
+static inline void clear_highpage_kasan_tagged(struct page *page)
+{
+	u8 tag;
+
+	tag = page_kasan_tag(page);
+	page_kasan_tag_reset(page);
+	clear_highpage(page);
+	page_kasan_tag_set(page, tag);
+}
+
 #ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
 
 static inline void tag_clear_highpage(struct page *page)
--- a/mm/page_alloc.c~mm-introduce-clear_highpage_kasan_tagged
+++ a/mm/page_alloc.c
@@ -1310,12 +1310,8 @@ static void kernel_init_pages(struct pag
 
 	/* s390's use of memset() could override KASAN redzones. */
 	kasan_disable_current();
-	for (i = 0; i < numpages; i++) {
-		u8 tag = page_kasan_tag(page + i);
-		page_kasan_tag_reset(page + i);
-		clear_highpage(page + i);
-		page_kasan_tag_set(page + i, tag);
-	}
+	for (i = 0; i < numpages; i++)
+		clear_highpage_kasan_tagged(page + i);
 	kasan_enable_current();
 }
 
_

Patches currently in -mm which might be from andreyknvl@google.com are

mm-rename-kernel_init_free_pages-to-kernel_init_pages.patch
mm-introduce-clear_highpage_kasan_tagged.patch
kasan-fix-zeroing-vmalloc-memory-with-hw_tags.patch