On Wed, Oct 08, 2014 at 09:25:27AM -0400, 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 the PMD would cover blocks out of the file */ > + if ((pgoff | PG_PMD_COLOUR) >= size) > + return VM_FAULT_FALLBACK; IIUC, zero pading would work too. > + > + memset(&bh, 0, sizeof(bh)); > + block = ((sector_t)pgoff & ~PG_PMD_COLOUR) << (PAGE_SHIFT - blkbits); > + > + /* Start by seeing if we already have an allocated block */ > + bh.b_size = PMD_SIZE; > + length = get_block(inode, block, &bh, 0); This makes me confused. get_block() return zero on success, right? Why the var called 'lenght'? > + sector = bh.b_blocknr << (blkbits - 9); > + length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn, bh.b_size); > + if (length < 0) > + goto sigbus; > + if (length < PMD_SIZE) > + goto fallback; > + if (pfn & PG_PMD_COLOUR) > + goto fallback; /* not aligned */ So, are you rely on pure luck to make get_block() allocate 2M aligned pfn? Not really productive. You would need assistance from fs and arch_get_unmapped_area() sides. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>