Re: [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible

Christoph Hellwig
2010-06-15T19:17:37Z

On Tue, Jun 15, 2010 at 03:13:09PM -0400, Rik van Riel wrote:
> Why? How about because you know the stack is not big enough
> to have the XFS call path on it twice? :)
>
> Isn't the whole purpose of this patch series to prevent writepage
> from being called by the VM, when invoked from a deep callstack
> like xfs writepage?

It's not invoked from xfs writepage, but from xfs_file_aio_write via
generic_file_buffered_write. Which isn't actually an all that deep
callstack, just en example of one that's alread bad enough to overflow
the stack.

> That sounds a lot like simply wanting to not have GFP_FS...

There's no point in sprinkling random GFP_NOFS flags. It's not just
the filesystem code that uses a lot of stack.