Re: [PATCH 3/5] mm: Add kmalloc NULL tests

Johannes Weiner
2009-07-30T19:12:14Z

On Thu, Jul 30, 2009 at 08:35:59PM +0200, JÃ¶rn Engel wrote:
> On Thu, 30 July 2009 17:36:58 +0200, Johannes Weiner wrote:
> > On Thu, Jul 30, 2009 at 04:10:22PM +0200, Julia Lawall wrote:
> >
> > > diff --git a/mm/slab.c b/mm/slab.c
> > > index 7b5d4de..972e427 100644
> > > --- a/mm/slab.c
> > > +++ b/mm/slab.c
> > > @@ -1502,6 +1502,7 @@ void __init kmem_cache_init(void)
> > >
> > > ptr = kmalloc(sizeof(struct arraycache_init), GFP_NOWAIT);
> > >
> > > + BUG_ON(!ptr);
> > > BUG_ON(cpu_cache_get(&cache_cache) != &initarray_cache.cache);
> > > memcpy(ptr, cpu_cache_get(&cache_cache),
> > > sizeof(struct arraycache_init));
> >
> > This does not change the end result when the allocation fails: you get
> > a stacktrace and a kernel panic. Leaving it as is saves a line of
> > code.
>
> According to http://lwn.net/Articles/342420/, there may be a subtle
> difference.

You will probably have a hard time establishing a userspace mapping
before slab is initializied :)