Re: [PATCH v2 sl-b 2/5] mm: Make mem_dump_obj() handle NULL and zero-sized pointers

[Paul E. McKenney]

On Wed, Dec 09, 2020 at 06:48:47PM +0100, Vlastimil Babka wrote:
> On 12/9/20 2:13 AM, paulmck@xxxxxxxxxx wrote:
> > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
> > 
> > This commit makes mem_dump_obj() call out NULL and zero-sized pointers
> > specially instead of classifying them as non-paged memory.
> > 
> > Cc: Christoph Lameter <cl@xxxxxxxxx>
> > Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> > Cc: David Rientjes <rientjes@xxxxxxxxxx>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > Cc: <linux-mm@xxxxxxxxx>
> > Reported-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> 
> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

Applied, thank you!

						Thanx, Paul

> > ---
> >  mm/util.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/util.c b/mm/util.c
> > index d0e60d2..8c2449f 100644
> > --- a/mm/util.c
> > +++ b/mm/util.c
> > @@ -985,7 +985,12 @@ int __weak memcmp_pages(struct page *page1, struct page *page2)
> >  void mem_dump_obj(void *object)
> >  {
> >  	if (!virt_addr_valid(object)) {
> > -		pr_cont(" non-paged (local) memory.\n");
> > +		if (object == NULL)
> > +			pr_cont(" NULL pointer.\n");
> > +		else if (object == ZERO_SIZE_PTR)
> > +			pr_cont(" zero-size pointer.\n");
> > +		else
> > +			pr_cont(" non-paged (local) memory.\n");
> >  		return;
> >  	}
> >  	if (kmem_valid_obj(object)) {
> > 
>