Re: [PATCH v6 00/37] Memory allocation profiling

Kent Overstreet
2024-04-25T03:26:13Z

On Wed, Apr 24, 2024 at 06:59:01PM -0700, Kees Cook wrote:
> On Thu, Mar 21, 2024 at 09:36:22AM -0700, Suren Baghdasaryan wrote:
> > Low overhead [1] per-callsite memory allocation profiling. Not just for
> > debug kernels, overhead low enough to be deployed in production.
>
> Okay, I think I'm holding it wrong. With next-20240424 if I set:
>
> CONFIG_CODE_TAGGING=y
> CONFIG_MEM_ALLOC_PROFILING=y
> CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT=y
>
> My test system totally freaks out:
>
> ...
> SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
> Oops: general protection fault, probably for non-canonical address 0xc388d881e4808550: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 0 PID: 0 Comm: swapper Not tainted 6.9.0-rc5-next-20240424 #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> RIP: 0010:__kmalloc_node_noprof+0xcd/0x560
>
> Which is:
>
> __kmalloc_node_noprof+0xcd/0x560:
> __slab_alloc_node at mm/slub.c:3780 (discriminator 2)
> (inlined by) slab_alloc_node at mm/slub.c:3982 (discriminator 2)
> (inlined by) __do_kmalloc_node at mm/slub.c:4114 (discriminator 2)
> (inlined by) __kmalloc_node_noprof at mm/slub.c:4122 (discriminator 2)
>
> Which is:
>
> tid = READ_ONCE(c->tid);
>
> I haven't gotten any further than that; I'm EOD. Anyone seen anything
> like this with this series?

I certainly haven't. That looks like some real corruption, we're in slub
internal data structures and derefing a garbage address. Check kasan and
all that?