From 3770e52fd4ec40ebee16ba19ad6c09dc0b52739b Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Mon, 30 Jan 2023 14:07:26 +0100 Subject: [PATCH] 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 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 Acked-by: Michal Hocko Reviewed-by: Pasha Tatashin Cc: Alexander Duyck Cc: Alexander Potapenko Cc: Alex Sierra Cc: David Hildenbrand Cc: Hugh Dickins Cc: John Hubbard Cc: Liam R. Howlett Cc: Matthew Wilcox Cc: Naoya Horiguchi Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- include/linux/mm.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 8f857163ac89..f13f20258ce9 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -137,7 +137,7 @@ extern int mmap_rnd_compat_bits __read_mostly; * define their own version of this macro in */ #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; -- 2.11.0