Re: [PATCH] resolve duplicate flag no for PG_lazyfree

[Andrew Morton <akpm@linux-foundation.org>]

On Mon, 14 May 2007 14:06:19 -0400
Theodore Tso <tytso@mit.edu> wrote:

> On Sun, May 13, 2007 at 10:46:30PM -0700, Andrew Morton wrote:
> > otoh, the intersection between pages which are PageBooked() and pages which
> > are PageLazyFree() should be zreo, so it'd be good to actually formalise
> > this reuse within the ext4 patches.
> > 
> > otoh2, PageLazyFree() could have reused PG_owner_priv_1.
> > 
> > Rik, Ted: any thoughts?  We do need to scrimp on page flags: when we
> > finally run out, we're screwed.
> 
> It makes sense to me.  PG_lazyfree is currently only in -mm, right?

Ah, yes, I got confused, sorry.

>  I
> don't see it in my git tree.  It would probably would be a good idea
> to make sure that we check to add some sanity checking code if it
> isn't there already that PG_lazyfree isn't already set when try to set
> PG_lazyfree (just in case there is a bug in the future which causes
> the should-never-happen case of trying lazy free a PageBooked page).
> 

Actually, I think the current status of
lazy-freeing-of-memory-through-madv_free.patch is "might not be needed".  I
_think_ we've determined that 0a27a14a62921b438bb6f33772690d345a089be6
sufficiently fixed the perfomance problems we had in there?