From: Chris Wilson <chris@chris-wilson.co.uk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
tip-bot2 for Peter Zijlstra <tip-bot2@linutronix.de>,
Qian Cai <cai@redhat.com>, x86 <x86@kernel.org>
Subject: Re: [tip: locking/core] lockdep: Fix usage_traceoverflow
Date: Wed, 28 Oct 2020 17:40:48 +0000 [thread overview]
Message-ID: <160390684819.31966.12048967113267928793@build.alporthouse.com> (raw)
In-Reply-To: <160381649396.10461.15013696719989662769@build.alporthouse.com>
Quoting Chris Wilson (2020-10-27 16:34:53)
> Quoting Peter Zijlstra (2020-10-27 15:45:33)
> > On Tue, Oct 27, 2020 at 01:29:10PM +0000, Chris Wilson wrote:
> >
> > > <4> [304.908891] hm#2, depth: 6 [6], 3425cfea6ff31f7f != 547d92e9ec2ab9af
> > > <4> [304.908897] WARNING: CPU: 0 PID: 5658 at kernel/locking/lockdep.c:3679 check_chain_key+0x1a4/0x1f0
> >
> > Urgh, I don't think I've _ever_ seen that warning trigger.
> >
> > The comments that go with it suggest memory corruption is the most
> > likely trigger of it. Is it easy to trigger?
>
> For the automated CI, yes, the few machines that run that particular HW
> test seem to hit it regularly. I have not yet reproduced it for myself.
> I thought it looked like something kasan would provide some insight for
> and we should get a kasan run through CI over the w/e. I suspect we've
> feed in some garbage and called it a lock.
I tracked it down to a second invocation of lock_acquire_shared_recursive()
intermingled with some other regular mutexes (in this case ww_mutex).
We hit this path in validate_chain():
/*
* Mark recursive read, as we jump over it when
* building dependencies (just like we jump over
* trylock entries):
*/
if (ret == 2)
hlock->read = 2;
and that is modifying hlock_id() and so the chain-key, after it has
already been computed.
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 035f81b1cc87..f193f756e1e3 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -4831,7 +4831,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (!validate_chain(curr, hlock, chain_head, chain_key))
return 0;
- curr->curr_chain_key = chain_key;
+ curr->curr_chain_key = iterate_chain_key(chain_key, hlock_id(hlock));
curr->lockdep_depth++;
check_chain_key(curr);
works as a heavy hammer.
-Chris
next prev parent reply other threads:[~2020-10-28 21:58 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 14:31 lockdep null-ptr-deref Qian Cai
2020-09-29 23:08 ` Boqun Feng
2020-09-30 9:16 ` Peter Zijlstra
2020-09-30 9:49 ` Peter Zijlstra
2020-09-30 12:18 ` Boqun Feng
2020-09-30 19:02 ` Peter Zijlstra
2020-10-02 12:36 ` Boqun Feng
2020-10-02 13:09 ` Peter Zijlstra
2020-10-02 13:35 ` Boqun Feng
2020-10-02 10:06 ` Peter Zijlstra
2020-10-02 13:40 ` Qian Cai
2020-10-07 16:20 ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra
2020-10-27 11:29 ` Chris Wilson
2020-10-27 11:59 ` Peter Zijlstra
2020-10-27 12:30 ` Peter Zijlstra
2020-10-27 12:48 ` Peter Zijlstra
2020-10-27 14:13 ` Chris Wilson
2020-10-31 11:30 ` [tip: locking/urgent] lockdep: Fix nr_unused_locks accounting tip-bot2 for Peter Zijlstra
2020-10-27 13:29 ` [tip: locking/core] lockdep: Fix usage_traceoverflow Chris Wilson
2020-10-27 15:45 ` Peter Zijlstra
2020-10-27 16:34 ` Chris Wilson
2020-10-28 17:40 ` Chris Wilson [this message]
2020-10-28 18:06 ` Chris Wilson
2020-10-28 19:42 ` Peter Zijlstra
2020-10-28 19:59 ` Peter Zijlstra
2020-10-30 3:51 ` Boqun Feng
2020-10-30 9:38 ` Peter Zijlstra
2020-10-30 9:55 ` Peter Zijlstra
2020-11-02 5:37 ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-02 5:37 ` [PATCH 2/2] lockdep/selftest: Add spin_nest_lock test Boqun Feng
2020-12-03 10:35 ` [tip: locking/core] " tip-bot2 for Boqun Feng
2020-11-05 6:25 ` [PATCH 1/2] lockdep: Avoid to modify chain keys in validate_chain() Boqun Feng
2020-11-10 17:28 ` Peter Zijlstra
2020-11-11 8:23 ` [tip: locking/urgent] " tip-bot2 for Boqun Feng
2020-10-09 7:58 ` [tip: locking/core] lockdep: Fix usage_traceoverflow tip-bot2 for Peter Zijlstra
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