Hi Hyeonggon,

On Wed, Aug 31, 2022 at 10:04:41PM +0800, Hyeonggon Yoo wrote:
> On Wed, Aug 31, 2022 at 03:30:51PM +0800, Feng Tang wrote:
> > When testing the linux-next kernel, kfence's kunit test reported some
> > errors:
> > 
> >   [   12.812412]     not ok 7 - test_double_free
> >   [   13.011968]     not ok 9 - test_invalid_addr_free
> >   [   13.438947]     not ok 11 - test_corruption
> >   [   18.635647]     not ok 18 - test_kmalloc_aligned_oob_write
> > 
> > Further check shows there is the "common kmalloc" patchset from
> > Hyeonggon Yoo, which cleanup the kmalloc code and make a better
> > sharing of slab/slub. There is some function name change around it,
> > which was not recognized by current kfence function name handling
> > code, and interpreted as error.
> > 
> > Add new function name "__kmem_cache_free" to make it known to kfence.
> > 
> > Signed-off-by: Feng Tang <feng.tang@intel.com>
> > ---
> >  mm/kfence/report.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/mm/kfence/report.c b/mm/kfence/report.c
> > index f5a6d8ba3e21..7e496856c2eb 100644
> > --- a/mm/kfence/report.c
> > +++ b/mm/kfence/report.c
> > @@ -86,6 +86,7 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
> >  		/* Also the *_bulk() variants by only checking prefixes. */
> >  		if (str_has_prefix(buf, ARCH_FUNC_PREFIX "kfree") ||
> >  		    str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_free") ||
> > +		    str_has_prefix(buf, ARCH_FUNC_PREFIX "__kmem_cache_free") ||
> >  		    str_has_prefix(buf, ARCH_FUNC_PREFIX "__kmalloc") ||
> >  		    str_has_prefix(buf, ARCH_FUNC_PREFIX "kmem_cache_alloc"))
> >  			goto found;
> > -- 
> > 2.27.0
> > 
> 
> Thank you for catching this!
> 
> Unfortunately not reproducible on my environment with linux-next (IDK why).

Maybe it's about the kernel config, or gcc version?

The head commit of next tree I tested is at:

7fd22855300e [Stephen Rothwell] Add linux-next specific files for 20220831 Wed Aug 31 15:48:36 2022 +1000

My gcc version is: "gcc (Ubuntu 10.3.0-1ubuntu1~20.10) 10.3.0"

I also attached the kernel config and the dmesg log which has the kfence
unit text info (the kernel is boot in a qemu with debian rootfs).


> Maybe you can include those functions too?
> 
> - __kmem_cache_alloc_node
> - kmalloc_[node_]trace, kmalloc_large[_node]

Though I threw the patch out, I have to admit I know very little about kfence
internals, will leave it to kfence developers :) (I saw Macro Elver already
replied).

Thanks,
Feng


> -- 
> Thanks,
> Hyeonggon