From: Nick Piggin Convert special mapping install from nopage to fault. This requires a small special case in the do_linear_fault calculation in order to handle vmas without ->vm_file set. Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton --- mm/memory.c | 10 +++++++--- mm/mmap.c | 19 +++++++++---------- 2 files changed, 16 insertions(+), 13 deletions(-) diff -puN mm/memory.c~mm-special-mapping-nopage mm/memory.c --- a/mm/memory.c~mm-special-mapping-nopage +++ a/mm/memory.c @@ -2286,9 +2286,13 @@ static int do_linear_fault(struct mm_str unsigned long address, pte_t *page_table, pmd_t *pmd, int write_access, pte_t orig_pte) { - pgoff_t pgoff = (((address & PAGE_MASK) - - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; - unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); + pgoff_t pgoff; + unsigned int flags; + + pgoff = (((address) - vma->vm_start) >> PAGE_SHIFT); + if (likely(vma->vm_file)) + pgoff += vma->vm_pgoff; + flags = (write_access ? FAULT_FLAG_WRITE : 0); pte_unmap(page_table); return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); diff -puN mm/mmap.c~mm-special-mapping-nopage mm/mmap.c --- a/mm/mmap.c~mm-special-mapping-nopage +++ a/mm/mmap.c @@ -2165,24 +2165,23 @@ int may_expand_vm(struct mm_struct *mm, } -static struct page *special_mapping_nopage(struct vm_area_struct *vma, - unsigned long address, int *type) +static int special_mapping_fault(struct vm_area_struct *vma, + struct vm_fault *vmf) { + pgoff_t pgoff = vmf->pgoff; struct page **pages; - BUG_ON(address < vma->vm_start || address >= vma->vm_end); - - address -= vma->vm_start; - for (pages = vma->vm_private_data; address > 0 && *pages; ++pages) - address -= PAGE_SIZE; + for (pages = vma->vm_private_data; pgoff && *pages; ++pages) + pgoff--; if (*pages) { struct page *page = *pages; get_page(page); - return page; + vmf->page = page; + return 0; } - return NOPAGE_SIGBUS; + return VM_FAULT_SIGBUS; } /* @@ -2194,7 +2193,7 @@ static void special_mapping_close(struct static struct vm_operations_struct special_mapping_vmops = { .close = special_mapping_close, - .nopage = special_mapping_nopage, + .fault = special_mapping_fault, }; /* _