On Mon, Sep 17, 2007 at 12:29:51PM -0700, Mingming Cao wrote:

The problem with this patch, as Andreas Dilger pointed today in ext4
interlock call, for 1k,2k block size ext2/3/4, get_free_pages() waste
1/3-1/2 page space. 

What was the originally intention to set up slabs for committed_data(and
frozen_buffer) in JBD? Why not using kmalloc?

kmalloc is using slabs :)

The intent was to avoid the wasted memory, but as we've repeated a gazillion
times wasted memory on a rather rare codepath doesn't really matter when
you just crash random storage drivers otherwise.