Commit 3770e52f authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Andrew Morton
Browse files

mm: extend max struct page size for kmsan 

After x86 enabled support for KMSAN, it has become possible to have larger
'struct page' than was expected when commit 5470dea4 ("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: 5470dea4 ("mm: use mm_zero_struct_page from SPARC on all 64b architectures")
Fixes: 4ca8cc8d ("x86: kmsan: enable KMSAN builds for x86")
Fixes: f80be457 ("kmsan: add KMSAN runtime core")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Reviewed-by: default avatarPasha 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ac86f547

include/linux/mm.h

+9 −3
Original line number Diff line number Diff line
@@ -137,7 +137,7 @@ 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,
@@ -148,12 +148,18 @@ 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;