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Date: Tue, 19 Mar 2024 13:51:29 -0400
From: Scott Mayhew <smayhew@redhat.com>
To: Nico Pache <npache@redhat.com>
Cc: linux-nfs@vger.kernel.org, kunit-dev@googlegroups.com
Subject: Re: [BUG REPORT] not ok 1 Derive Kc subkey for camellia128-cts-cmac
Message-ID: <ZfnQoTn-xN72HppD@aion>
References: <20240307140923.16598-1-npache@redhat.com>
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In-Reply-To: <20240307140923.16598-1-npache@redhat.com>

Hi,

On Thu, 07 Mar 2024, Nico Pache wrote:

> Hi,
> 
> One of the RFC 6803 key derivation kunit subtests is failing.
> 
> cki-project data warehouse : https://datawarehouse.cki-project.org/issue/2514
> 
> Arches: X86_64, ARM64, S390x, ppc64le
> First Appeared: ~6.8.rc2
> 
> TRACE:
> # Subtest: RFC 6803 key derivation
>     # RFC 6803 key derivation: ASSERTION FAILED at net/sunrpc/auth_gss/gss_krb5_test.c:63
>     Expected err == 0, but
>         err == -110 (0xffffffffffffff92)
>         not ok 1 Derive Kc subkey for camellia128-cts-cmac
>         ok 2 Derive Ke subkey for camellia128-cts-cmac
>         ok 3 Derive Ki subkey for camellia128-cts-cmac
>         ok 4 Derive Kc subkey for camellia256-cts-cmac
>         ok 5 Derive Ke subkey for camellia256-cts-cmac
>         ok 6 Derive Ki subkey for camellia256-cts-cmac
>     # RFC 6803 key derivation: pass:5 fail:1 skip:0 total:6
>     not ok 1 RFC 6803 key derivation

This was broken by:
c72a870926c2 kunit: add ability to run tests after boot using debugfs

__kunit_test_suites_init() runs any time a kernel module is loaded, via
the "kunit_mod_nb" notifier_block... even if the kernel module has no
kunit tests.  But now __kunit_test_suites_init() also locks a mutex,
which is a problem if a kunit test itself needs to load a kernel module
(which the gss_krb5_test module does).

This fixes it for me:

---8<---
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 088489856db8..18af9453632b 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -707,6 +707,9 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
 {
        unsigned int i;
 
+       if (num_suites == 0)
+               return 0;
+
        if (!kunit_enabled() && num_suites > 0) {
                pr_info("kunit: disabled\n");
                return 0;
---8<---

More detail below:

Here's the modprobe command where I loaded the gss_krb5_test module.  This
process has the "kunit_run_lock" mutex locked:

PID: 1468     TASK: ffff9aed0ac20000  CPU: 0    COMMAND: "modprobe"
 #0 [ffffba974196f6f8] __schedule at ffffffff83fd85f5
 #1 [ffffba974196f7b0] schedule at ffffffff83fd9672
 #2 [ffffba974196f7c8] schedule_timeout at ffffffff83fe0308
 #3 [ffffba974196f818] wait_for_completion_timeout at ffffffff83fda3d4
 #4 [ffffba974196f878] kunit_try_catch_run at ffffffffc0d5e851 [kunit]
 #5 [ffffba974196f8c8] kunit_run_tests at ffffffffc0d5c0ea [kunit]
 #6 [ffffba974196fb78] __kunit_test_suites_init at ffffffffc0d5c9af [kunit]
 #7 [ffffba974196fb98] kunit_module_notify at ffffffffc0d5ba4b [kunit]
 #8 [ffffba974196fc08] notifier_call_chain at ffffffff8314647a
 #9 [ffffba974196fc40] blocking_notifier_call_chain_robust at ffffffff83146565
#10 [ffffba974196fc88] load_module at ffffffff831e1935
#11 [ffffba974196fde8] __do_sys_init_module at ffffffff831e1fba
#12 [ffffba974196fec0] do_syscall_64 at ffffffff83fc3461
#13 [ffffba974196fee8] do_user_addr_fault at ffffffff830979df
#14 [ffffba974196ff28] exc_page_fault at ffffffff83fc9c7f
#15 [ffffba974196ff50] entry_SYSCALL_64_after_hwframe at ffffffff840000ea
    RIP: 00007ff1f272b4ae  RSP: 00007ffd45db8f68  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 000055bf4c0c4b20  RCX: 00007ff1f272b4ae
    RDX: 000055bf4b204e79  RSI: 0000000000099691  RDI: 000055bf4cbfd130
    RBP: 00007ffd45db9020   R8: 000055bf4c0c4010   R9: 0000000000000007
    R10: 0000000000000001  R11: 0000000000000246  R12: 000055bf4b204e79
    R13: 0000000000040000  R14: 000055bf4c0c4c50  R15: 000055bf4c0c4390
    ORIG_RAX: 00000000000000af  CS: 0033  SS: 002b

Here's the kunit test case running.  It's trying to allocate "cmac(camellia)"
via crypto_alloc_shash():

PID: 1508     TASK: ffff9aed155d0000  CPU: 1    COMMAND: "kunit_try_catch"
 #0 [ffffba974194fba0] __schedule at ffffffff83fd85f5
 #1 [ffffba974194fc58] schedule at ffffffff83fd9672
 #2 [ffffba974194fc70] schedule_timeout at ffffffff83fe0308
 #3 [ffffba974194fcc0] wait_for_completion_killable_timeout at ffffffff83fda708
 #4 [ffffba974194fd20] crypto_larval_wait at ffffffff83747fb4
 #5 [ffffba974194fd38] crypto_alg_mod_lookup at ffffffff83748252
 #6 [ffffba974194fd70] crypto_alloc_tfm_node at ffffffff83748492
 #7 [ffffba974194fdb0] krb5_kdf_feedback_cmac at ffffffffc0d76bb2 [rpcsec_gss_krb5]
 #8 [ffffba974194fe30] kdf_case at ffffffffc0d800a8 [gss_krb5_test]
 #9 [ffffba974194fe80] kunit_try_run_case at ffffffffc0d5bb54 [kunit]
#10 [ffffba974194fee8] kunit_generic_run_threadfn_adapter at ffffffffc0d5e797 [kunit]
#11 [ffffba974194fef8] kthread at ffffffff8313eda5
#12 [ffffba974194ff30] ret_from_fork at ffffffff830414a1
#13 [ffffba974194ff50] ret_from_fork_asm at ffffffff830039ab

Here the crypto manager is trying to modprobe the camellia kernel module via a
usermodehelper call:

PID: 1511     TASK: ffff9aed04630000  CPU: 3    COMMAND: "cryptomgr_probe"
 #0 [ffffba974195fb88] __schedule at ffffffff83fd85f5
 #1 [ffffba974195fc40] schedule at ffffffff83fd9672
 #2 [ffffba974195fc58] schedule_timeout at ffffffff83fe03c1
 #3 [ffffba974195fca8] wait_for_completion_state at ffffffff83fdb06d
 #4 [ffffba974195fd18] call_usermodehelper_exec at ffffffff83130313
 #5 [ffffba974195fd68] __request_module at ffffffff831e325d
 #6 [ffffba974195fe28] crypto_alg_mod_lookup at ffffffff83748220
 #7 [ffffba974195fe60] crypto_grab_spawn at ffffffff83749ff7
 #8 [ffffba974195fe98] cmac_create at ffffffff8375c2f0
 #9 [ffffba974195fed8] cryptomgr_probe at ffffffff83754a93
#10 [ffffba974195fef8] kthread at ffffffff8313eda5
#11 [ffffba974195ff30] ret_from_fork at ffffffff830414a1
#12 [ffffba974195ff50] ret_from_fork_asm at ffffffff830039ab

And here's the resulting modprobe command, which is stuck waiting on the
"kunit_run_lock" mutex:

PID: 1512     TASK: ffff9aed143fafc0  CPU: 2    COMMAND: "modprobe"
 #0 [ffffba9741957990] __schedule at ffffffff83fd85f5
 #1 [ffffba9741957a48] schedule at ffffffff83fd9672
 #2 [ffffba9741957a60] schedule_preempt_disabled at ffffffff83fd9cb5
 #3 [ffffba9741957a68] __mutex_lock.constprop.0 at ffffffff83fdc57a
 #4 [ffffba9741957ae8] __kunit_test_suites_init at ffffffffc0d5c95a [kunit]
 #5 [ffffba9741957b08] kunit_module_notify at ffffffffc0d5ba4b [kunit]
 #6 [ffffba9741957b78] notifier_call_chain at ffffffff8314647a
 #7 [ffffba9741957bb0] blocking_notifier_call_chain_robust at ffffffff83146565
 #8 [ffffba9741957bf8] load_module at ffffffff831e1935
 #9 [ffffba9741957d58] __do_sys_init_module at ffffffff831e1fba
#10 [ffffba9741957e30] do_syscall_64 at ffffffff83fc3461
#11 [ffffba9741957e48] __vm_munmap at ffffffff833bcdeb
#12 [ffffba9741957ee8] do_syscall_64 at ffffffff83fc3470
#13 [ffffba9741957f50] entry_SYSCALL_64_after_hwframe at ffffffff840000ea
    RIP: 00007f8ba092b4ae  RSP: 00007ffc771e0378  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 00005572137e6e40  RCX: 00007f8ba092b4ae
    RDX: 0000557211c4de79  RSI: 0000000000080451  RDI: 00007f8b9ff90010
    RBP: 00007ffc771e0430   R8: 00005572137e6010   R9: 0000000000000007
    R10: 0000000000000001  R11: 0000000000000246  R12: 0000557211c4de79
    R13: 0000000000040000  R14: 00005572137e73b0  R15: 00005572137e6400
    ORIG_RAX: 00000000000000af  CS: 0033  SS: 002b

The camellia module doesn't even have any kunit tests, so __kunit_test_suites_init()
is waiting to lock the "kunit_run_lock" mutex for nothing:

crash> module -o | grep num_kunit
  [0x478] int num_kunit_init_suites;
  [0x488] int num_kunit_suites;
crash> mod | grep camellia
ffffffffc0da15c0  camellia_x86_64                ffffffffc0d99000    57344  (not loaded)  [CONFIG_KALLSYMS]
crash> px 0xffffffffc0da15c0+0x478
$1 = 0xffffffffc0da1a38
crash> px 0xffffffffc0da15c0+0x488
$2 = 0xffffffffc0da1a48
crash> rd 0xffffffffc0da1a38
ffffffffc0da1a38:  0000000000000000                    ........
crash> rd 0xffffffffc0da1a48
ffffffffc0da1a48:  0000000000000000                    ........

-Scott
> -- 
> 2.44.0
> 
>