On Sat, 2007-03-24 at 23:09 +0100, Miklos Szeredi wrote:
> From: Miklos Szeredi <[EMAIL PROTECTED]>
>
> Dirty page accounting/limiting doesn't work for nonlinear mappings, so
> for non-ram backed filesystems emulate with linear mappings. This
> retains ABI compatibility with previous kernels at minimal code cost.
>
> All known users of nonlinear mappings actually use tmpfs, so this
> shouldn't have any negative effect.
>
> Signed-off-by: Miklos Szeredi <[EMAIL PROTECTED]>
Acked-by: Peter Zijlstra <[EMAIL PROTECTED]>
> ---
>
> Index: linux-2.6.21-rc4-mm1/mm/fremap.c
> ===================================================================
> --- linux-2.6.21-rc4-mm1.orig/mm/fremap.c 2007-03-24 22:30:05.000000000
> +0100
> +++ linux-2.6.21-rc4-mm1/mm/fremap.c 2007-03-24 22:37:59.000000000 +0100
> @@ -181,6 +181,24 @@ asmlinkage long sys_remap_file_pages(uns
> goto retry;
> }
> mapping = vma->vm_file->f_mapping;
> + /*
> + * page_mkclean doesn't work on nonlinear vmas, so if dirty
> + * pages need to be accounted, emulate with linear vmas.
> + */
> + if (mapping_cap_account_dirty(mapping)) {
> + unsigned long addr;
> +
> + flags &= MAP_NONBLOCK;
> + addr = mmap_region(vma->vm_file, start, size, flags,
> + vma->vm_flags, pgoff, 1);
> + if (IS_ERR_VALUE(addr))
> + err = addr;
> + else {
> + BUG_ON(addr != start);
> + err = 0;
> + }
> + goto out;
> + }
> spin_lock(&mapping->i_mmap_lock);
> flush_dcache_mmap_lock(mapping);
> vma->vm_flags |= VM_NONLINEAR;
-
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