Re: [PATCH-tip 0/5] locking/locktorture: Fix locktorture ww_mutex test problems

From: Waiman Long <longman@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Davidlohr Bueso <dave@stgolabs.net>,
	linux-kernel@vger.kernel.org, Juri Lelli <juri.lelli@redhat.com>
Subject: Re: [PATCH-tip 0/5] locking/locktorture: Fix locktorture ww_mutex test problems
Date: Fri, 19 Mar 2021 11:29:40 -0400	[thread overview]
Message-ID: <2e195484-e011-faab-f6b0-1cfeecc5f3bf@redhat.com> (raw)
In-Reply-To: <20210319111629.GB4029764@gmail.com>

On 3/19/21 7:16 AM, Ingo Molnar wrote:
> * Waiman Long <longman@redhat.com> wrote:
>
>> This is a follow-up patch series for the previous patchset on fixing
>> locktorture ww_mutex test problem [1]. The first 3 patches of that
>> series were merged into tip. It turns out that the last one of the
>> three wasn't quite right. So this patch series revert the last patch.
>>
>> The rests of the patch series fix the ww_mutex testing problem in
>> locktorture as well as removing the DEFINE_WW_MUTEX() macro from
>> include/linux/ww_mutex.h.
>>
>> [1] https://lore.kernel.org/lkml/20210316153119.13802-1-longman@redhat.com/
>>
>> Waiman Long (5):
>>    locking/ww_mutex: Revert "Treat ww_mutex_lock() like a trylock"
>>    locking/locktorture: Fix false positive circular locking splat in
>>      ww_mutex test
>>    locking/ww_mutex: Remove DEFINE_WW_MUTEX() macro
>>    locking/locktorture: Pass thread id to lock/unlock functions
>>    locking/locktorture: locking/locktorture: Fix incorrect use of
>>      ww_acquire_ctx in ww_mutex test
> Applied, thanks Waiman.
>
> I kept these two fixes in locking/urgent, for a v5.12 merge:
>
>    bee645788e07: ("locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire_fini()")
>    5de2055d31ea: ("locking/ww_mutex: Simplify use_ww_ctx & ww_ctx handling")
>
> As this bug could affect actual ww_mutex users.
>
> And queued up these four in locking/core, for a v5.13 merge:
>
>    8c52cca04f97: ("locking/locktorture: Fix incorrect use of ww_acquire_ctx in ww_mutex test")
>    aa3a5f31877e: ("locking/locktorture: Pass thread id to lock/unlock functions")
>    5261ced47f8e: ("locking/ww_mutex: Remove DEFINE_WW_MUTEX() macro")
>    2ea55bbba23e: ("locking/locktorture: Fix false positive circular locking splat in ww_mutex test")
>
> As these bugs are basically limited to a debugging facility.
>
> ( But we could also merge them into v5.12, if you think it's
>    justified. No strong opinions either way. )

I think v5.13 merge is fine. This problem exists for quite a while and 
no one notices it. So it is not really that urgent.

Thank a lot for the quick action.

Cheers,
Longman