| Subject | Re: [PATCH 05/30] mm: slb: add knowledge of reserve pages | From | Peter Zijlstra <> | Date | Tue, 12 Aug 2008 09:22:30 +0200 |
| |
On Tue, 2008-08-12 at 15:35 +1000, Neil Brown wrote: > On Thursday July 24, a.p.zijlstra@chello.nl wrote: > > Restrict objects from reserve slabs (ALLOC_NO_WATERMARKS) to allocation > > contexts that are entitled to it. This is done to ensure reserve pages don't > > leak out and get consumed. > > This looks good (we are still missing slob though, aren't we :-( )
I actually have that now, just needs some testing..
> > @@ -1526,7 +1540,7 @@ load_freelist: > > object = c->page->freelist; > > if (unlikely(!object)) > > goto another_slab; > > - if (unlikely(SLABDEBUG && PageSlubDebug(c->page))) > > + if (unlikely(PageSlubDebug(c->page) || c->reserve)) > > goto debug; > > This looks suspiciously like debugging code that you have left in. > Is it??
Its not, we need to force slub into the debug slow path when we have a reserve page, otherwise we cannot do the permission check on each allocation.
> > @@ -265,7 +267,8 @@ struct array_cache { > > unsigned int avail; > > unsigned int limit; > > unsigned int batchcount; > > - unsigned int touched; > > + unsigned int touched:1, > > + reserve:1; > > This sort of thing always worries me. > It is a per-cpu data structure so you won't get SMP races corrupting > fields. But you do get read-modify-write in place of simple updates. > I guess it's not a problem.. But it worries me :-)
Right,.. do people prefer I just add another int?
|