On 10/1/24 18:20, Vlastimil Babka wrote: > Guenter Roeck reports that the new slub kunit tests added by commit > 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and > test_leak_destroy()") cause a lockup on boot on several architectures > when the kunit tests are configured to be built-in and not modules. > > The test_kfree_rcu test invokes kfree_rcu() and boot sequence inspection > showed the runner for built-in kunit tests kunit_run_all_tests() is > called before setting system_state to SYSTEM_RUNNING and calling > rcu_end_inkernel_boot(), so this seems like a likely cause. So while I > was unable to reproduce the problem myself, skipping the test when the > slub_kunit module is built-in should avoid the issue. > > An alternative fix that was moving the call to kunit_run_all_tests() a > bit later in the boot was tried, but has broken tests with functions > marked as __init due to free_initmem() already being done. > > Fixes: 4e1c44b3db79 ("kunit, slub: add test_kfree_rcu() and test_leak_destroy()") > Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx> > Closes: https://lore.kernel.org/all/6fcb1252-7990-4f0d-8027-5e83f0fb9409@xxxxxxxxxxxx/ I hope you can confirm it helps, because the commit added two tests and I've only skipped one of them, as it's the one using kfree_rcu(), which is suspected. But the other is responsible for the (now suppressed) kmem_cache_destroy() warning, and maybe I'm missing something and it was actually that one causing the lockups. Since you mentioned the boot lockups happened on some x86_64 too, do you have a .config of the lockup case? I've tried tweaking some rcu options but still nothing. Thanks! > Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > Cc: Boqun Feng <boqun.feng@xxxxxxxxx> > Cc: Uladzislau Rezki <urezki@xxxxxxxxx> > Cc: rcu@xxxxxxxxxxxxxxx > Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx> > Cc: David Gow <davidgow@xxxxxxxxxx> > Cc: Rae Moar <rmoar@xxxxxxxxxx> > Cc: linux-kselftest@xxxxxxxxxxxxxxx > Cc: kunit-dev@xxxxxxxxxxxxxxxx > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > --- > lib/slub_kunit.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c > index 85d51ec09846d4fa219db6bda336c6f0b89e98e4..80e39f003344858722a544ad62ed84e885574054 100644 > --- a/lib/slub_kunit.c > +++ b/lib/slub_kunit.c > @@ -164,10 +164,16 @@ struct test_kfree_rcu_struct { > > static void test_kfree_rcu(struct kunit *test) > { > - struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu", > - sizeof(struct test_kfree_rcu_struct), > - SLAB_NO_MERGE); > - struct test_kfree_rcu_struct *p = kmem_cache_alloc(s, GFP_KERNEL); > + struct kmem_cache *s; > + struct test_kfree_rcu_struct *p; > + > + if (IS_BUILTIN(CONFIG_SLUB_KUNIT_TEST)) > + kunit_skip(test, "can't do kfree_rcu() when test is built-in"); > + > + s = test_kmem_cache_create("TestSlub_kfree_rcu", > + sizeof(struct test_kfree_rcu_struct), > + SLAB_NO_MERGE); > + p = kmem_cache_alloc(s, GFP_KERNEL); > > kfree_rcu(p, rcu); > kmem_cache_destroy(s); >