6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vasily Gorbik gor@linux.ibm.com
[ Upstream commit ff123eb7741638d55abf82fac090bb3a543c1e74 ]
Commit c98d2ecae08f ("s390/mm: Uncouple physical vs virtual address spaces") introduced a large_allowed() helper that restricts which mapping modes can use large pages. This change unintentionally prevented KASAN shadow mappings from using large pages, despite there being no reason to avoid them. In fact, large pages are preferred for performance.
Add POPULATE_KASAN_MAP_SHADOW to the allowed list in large_allowed() to restore large page mappings for KASAN shadows.
While large_allowed() isn't strictly necessary with current mapping modes since disallowed modes either don't map anything or fail alignment and size checks, keep it for clarity.
Fixes: c98d2ecae08f ("s390/mm: Uncouple physical vs virtual address spaces") Acked-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/boot/vmem.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c index 3fa28db2fe59f..824690427b61a 100644 --- a/arch/s390/boot/vmem.c +++ b/arch/s390/boot/vmem.c @@ -264,7 +264,17 @@ static unsigned long _pa(unsigned long addr, unsigned long size, enum populate_m
static bool large_allowed(enum populate_mode mode) { - return (mode == POPULATE_DIRECT) || (mode == POPULATE_IDENTITY) || (mode == POPULATE_KERNEL); + switch (mode) { + case POPULATE_DIRECT: + case POPULATE_IDENTITY: + case POPULATE_KERNEL: +#ifdef CONFIG_KASAN + case POPULATE_KASAN_MAP_SHADOW: +#endif + return true; + default: + return false; + } }
static bool can_large_pud(pud_t *pu_dir, unsigned long addr, unsigned long end,