On Mon, Dec 23, 2013 at 08:04:09AM -0700, Matthew Wilcox wrote: > On Mon, Dec 23, 2013 at 07:50:31AM -0700, Matthew Wilcox wrote: > > > > + pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; > > > > + size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > > > > + if (pgoff >= size) > > > > + return VM_FAULT_SIGBUS; > > > > + if ((pgoff | PG_PMD_COLOUR) >= size) > > > > + return VM_FAULT_FALLBACK; > > > > > > I don't think it's necessary to fallback in this case. > > > Do you care about SIGBUS behaviour or what? > > > > I'm looking to preserve the same behaviour we see with PTE mappings. I mean, > > it's supposed to be _transparent_ huge pages, right? > > Speaking of which ... we also need to check if the PMD is entirely within > the VMA. So, this is needed: > > @@ -308,6 +308,11 @@ static int do_xip_pmd_fault(struct vm_area_struct *vma, uns > /* Fall back to PTEs if we're going to COW */ > if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) > return VM_FAULT_FALLBACK; > + /* Fall back to PTEs if the mapping would extend outside the VMA */ > + if ((address & ~PMD_MASK) < vma->vm_start) > + return VM_FAULT_FALLBACK; > + if (ALIGN(address, PMD_SIZE) >= vma->vm_end) > + return VM_FAULT_FALLBACK; > > pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; > size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; > > I'll fold that into the next round of patches. Agree with this part. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
