Re: [RFC 0/8] Cpuset aware writeback

[Andrew Morton]

> On Wed, 17 Jan 2007 17:10:25 -0800 (PST) Christoph Lameter <clameter@xxxxxxx> wrote:
> On Wed, 17 Jan 2007, Andrew Morton wrote:
> 
> > > The inode lock is not taken when the page is dirtied.
> > 
> > The inode_lock is taken when the address_space's first page is dirtied.  It is
> > also taken when the address_space's last dirty page is cleaned.  So the place
> > where the inode is added to and removed from sb->s_dirty is, I think, exactly
> > the place where we want to attach and detach address_space.dirty_page_nodemask.
> 
> The problem there is that we do a GFP_ATOMIC allocation (no allocation 
> context) that may fail when the first page is dirtied. We must therefore 
> be able to subsequently allocate the nodemask_t in set_page_dirty(). 
> Otherwise the first failure will mean that there will never be a dirty 
> map for the inode/mapping.

True.  But it's pretty simple to change __mark_inode_dirty() to fix this.
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