From: Arnd Bergmann arnd@arndb.de
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 --- include/linux/mm.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
--- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -136,7 +136,7 @@ extern int mmap_rnd_compat_bits __read_m * 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 { 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;