Re: [PATCH] mm: add gfp_mask parameter to vm_map_ram()

Dave Chinner
2012-06-14T02:15:53Z

On Thu, Jun 14, 2012 at 09:49:02AM +0800, Fengguang Wu wrote:
> On Thu, Jun 14, 2012 at 11:20:26AM +1000, Dave Chinner wrote:
> >
> > Bug in vm_map_ram - it does an unconditional GFP_KERNEL allocation
> > here, and we are in a GFP_NOFS context. We can't pass a gfp_mask to
> > vm_map_ram(), so until vm_map_ram() grows that we can't fix it...
>
> This trivial patch should fix it.
>
> The only behavior change is the XFS part:
>
> @@ -406,7 +406,7 @@ _xfs_buf_map_pages(
>
> do {
> bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
> - -1, PAGE_KERNEL);
> + -1, GFP_NOFS, PAGE_KERNEL);

This function isn't always called in GFP_NOFS context - readahead
uses different memory allocation semantics (no retry, no warn), so
there are flags that tell it what to do. i.e.

- -1, PAGE_KERNEL);
+ -1, xb_to_gfp(flags), PAGE_KERNEL);

Otherwise looks fine to me...

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com