On Tue, Mar 10, 2009 at 08:22:10PM +0800, Wu Fengguang wrote:
> On Tue, Mar 10, 2009 at 11:55:23AM +0200, Pierre Ossman wrote:
> > On Tue, 10 Mar 2009 16:19:17 +0800
> > Wu Fengguang <fengguang.wu@intel.com> wrote:
> > 
> > > 
> > > Here is the initial patch and tool for finding the missing pages.
> > > 
> > > In the following example, the pages with no flags set is kind of too
> > > many (1816MB), but hopefully your missing pages will have PG_reserved
> > > or other flags set ;-)
> > > 
> > > # ./page-types
> > > L:locked E:error R:referenced U:uptodate D:dirty L:lru A:active S:slab W:writeback x:reclaim B:buddy r:reserved c:swapcache b:swapbacked
> > >  
> > 
> > Thanks. I'll have a look in a bit. Right now I'm very close to a
> > complete bisect. It is just ftrace commits left though, so I'm somewhat
> > sceptical that it is correct. ftrace isn't even turned on in the
> > kernels I've been testing.
> > 
> > The remaining commits are ec1bb60bb..6712e299.

Another tool to show the page locations with specified flags:

# ./page-areas 0x20000 | head
    offset      len         KB
        11        1        4KB
        13        3       12KB
        17        7       28KB
        25        1        4KB
        31        1        4KB
        33       31      124KB
        65       63      252KB
       129       15       60KB
       145        7       28KB

If we run eatmem or the following commands to take up free memory,
the missing pages will show up :-)

        dd if=/dev/zero of=/tmp/s bs=1M count=1 seek=1024
        cp /tmp/s /dev/null

Thanks,
Fengguang