Re: Possible regression in "slab, slub: skip unnecessary kasan_cache_shutdown()"

[Shakeel Butt <shakeelb@google.com>]

On Tue, Jun 19, 2018 at 8:19 AM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> On Tue, Jun 19, 2018 at 5:08 PM Shakeel Butt <shakeelb@google.com> wrote:
> > > > Are you using SLAB or SLUB? We stress kernel pretty heavily, but with
> > > > SLAB, and I suspect Shakeel may also be using SLAB. So if you are
> > > > using SLUB, there is significant chance that it's a bug in the SLUB
> > > > part of the change.
> > >
> > > Nice intuition; I am indeed using SLUB rather than SLAB...
> > >
> >
> > Can you try once with SLAB? Just to make sure that it is SLUB specific.
>
> Sorry, I meant to mention that earlier. I tried with SLAB; the crash
> does not occur. This appears to be SLUB-specific.

Jason, can you try the following patch?

---
 mm/slub.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/slub.c b/mm/slub.c
index a3b8467c14af..746cfe4515c2 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3673,9 +3673,17 @@ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
 
 bool __kmem_cache_empty(struct kmem_cache *s)
 {
+	int cpu;
 	int node;
 	struct kmem_cache_node *n;
 
+	for_each_online_cpu(cpu) {
+		struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+
+		if (c->page || slub_percpu_partial(c))
+			return false;
+	}
+
 	for_each_kmem_cache_node(s, node, n)
 		if (n->nr_partial || slabs_node(s, node))
 			return false;
-- 
2.18.0.rc1.244.gcf134e6275-goog