Re: [PATCH v2 sl-b 3/5] mm: Make mem_dump_obj() handle vmalloc() memory

Uladzislau Rezki
2020-12-09T19:39:51Z

On Wed, Dec 09, 2020 at 06:51:20PM +0100, Vlastimil Babka wrote:
> On 12/9/20 2:13 AM, paulmck@kernel.org wrote:
> > From: "Paul E. McKenney" <paulmck@kernel.org>
> >
> > This commit adds vmalloc() support to mem_dump_obj(). Note that the
> > vmalloc_dump_obj() function combines the checking and dumping, in
> > contrast with the split between kmem_valid_obj() and kmem_dump_obj().
> > The reason for the difference is that the checking in the vmalloc()
> > case involves acquiring a global lock, and redundant acquisitions of
> > global locks should be avoided, even on not-so-fast paths.
> >
> > Note that this change causes on-stack variables to be reported as
> > vmalloc() storage from kernel_clone() or similar, depending on the degree
> > of inlining that your compiler does. This is likely more helpful than
> > the earlier "non-paged (local) memory".
> >
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: <linux-mm@kvack.org>
> > Reported-by: Andrii Nakryiko <andrii@kernel.org>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
>
> ...
>
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -3431,6 +3431,18 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
> > }
> > #endif /* CONFIG_SMP */
> >
> > +bool vmalloc_dump_obj(void *object)
> > +{
> > + struct vm_struct *vm;
> > + void *objp = (void *)PAGE_ALIGN((unsigned long)object);
> > +
> > + vm = find_vm_area(objp);
> > + if (!vm)
> > + return false;
> > + pr_cont(" vmalloc allocated at %pS\n", vm->caller);
>
> Would it be useful to print the vm area boundaries too?
>
Do you mean va_start/va_end information?

--
Vlad Rezki