diff options
| -rw-r--r-- | include/linux/mm.h | 11 | ||||
| -rw-r--r-- | mm/huge_memory.c | 2 | ||||
| -rw-r--r-- | mm/memory.c | 2 |
3 files changed, 13 insertions, 2 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 27eb1bfbe704..ab7dadca4ea5 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -56,6 +56,17 @@ extern int sysctl_legacy_va_layout; #define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0)) #endif +/* + * To prevent common memory management code establishing + * a zero page mapping on a read fault. + * This macro should be defined within <asm/pgtable.h>. + * s390 does this to prevent multiplexing of hardware bits + * related to the physical page in case of virtualization. + */ +#ifndef mm_forbids_zeropage +#define mm_forbids_zeropage(X) (0) +#endif + extern unsigned long sysctl_user_reserve_kbytes; extern unsigned long sysctl_admin_reserve_kbytes; diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 74c78aa8bc2f..7e9c15cb93a9 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -805,7 +805,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, return VM_FAULT_OOM; if (unlikely(khugepaged_enter(vma))) return VM_FAULT_OOM; - if (!(flags & FAULT_FLAG_WRITE) && + if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm) && transparent_hugepage_use_zero_page()) { spinlock_t *ptl; pgtable_t pgtable; diff --git a/mm/memory.c b/mm/memory.c index 1cc6bfbd872e..d722d4f481c9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2640,7 +2640,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, return VM_FAULT_SIGBUS; /* Use the zero-page for reads */ - if (!(flags & FAULT_FLAG_WRITE)) { + if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) { entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), vma->vm_page_prot)); page_table = pte_offset_map_lock(mm, pmd, address, &ptl); |