From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 30 Jan 2023 13:07:26 +0000 (+0100)
Subject: mm: extend max struct page size for kmsan
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=974cfed82cc962eb9f656ac709f0902378f75e2a;p=users%2Fjedix%2Flinux-maple.git

mm: extend max struct page size for kmsan

commit 3770e52fd4ec40ebee16ba19ad6c09dc0b52739b upstream.

After x86 enabled support for KMSAN, it has become possible to have larger
'struct page' than was expected when commit 5470dea49f53 ("mm: use
mm_zero_struct_page from SPARC on all 64b architectures") was merged:

include/linux/mm.h:156:10: warning: no case matching constant switch condition '96'
        switch (sizeof(struct page)) {

Extend the maximum accordingly.

Link: https://lkml.kernel.org/r/20230130130739.563628-1-arnd@kernel.org
Fixes: 5470dea49f53 ("mm: use mm_zero_struct_page from SPARC on all 64b architectures")
Fixes: 4ca8cc8d1bbe ("x86: kmsan: enable KMSAN builds for x86")
Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 974ccca609d2..e5e8acf8eb89 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -136,7 +136,7 @@ extern int mmap_rnd_compat_bits __read_mostly;
  * define their own version of this macro in <asm/pgtable.h>
  */
 #if BITS_PER_LONG == 64
-/* This function must be updated when the size of struct page grows above 80
+/* This function must be updated when the size of struct page grows above 96
  * or reduces below 56. The idea that compiler optimizes out switch()
  * statement, and only leaves move/store instructions. Also the compiler can
  * combine write statements if they are both assignments and can be reordered,
@@ -147,12 +147,18 @@ static inline void __mm_zero_struct_page(struct page *page)
 {
 	unsigned long *_pp = (void *)page;
 
-	 /* Check that struct page is either 56, 64, 72, or 80 bytes */
+	 /* Check that struct page is either 56, 64, 72, 80, 88 or 96 bytes */
 	BUILD_BUG_ON(sizeof(struct page) & 7);
 	BUILD_BUG_ON(sizeof(struct page) < 56);
-	BUILD_BUG_ON(sizeof(struct page) > 80);
+	BUILD_BUG_ON(sizeof(struct page) > 96);
 
 	switch (sizeof(struct page)) {
+	case 96:
+		_pp[11] = 0;
+		fallthrough;
+	case 88:
+		_pp[10] = 0;
+		fallthrough;
 	case 80:
 		_pp[9] = 0;
 		fallthrough;