From: Qian Cai <cai@lca•pw>
To: "Paul E. McKenney" <paulmck@kernel•org>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
Linux Next Mailing List <linux-next@vger•kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger•kernel.org>,
Madhuparna Bhowmik <madhuparnabhowmik10@gmail•com>,
Amol Grover <frextrite@gmail•com>,
Dmitry Vyukov <dvyukov@google•com>
Subject: Re: Default enable RCU list lockdep debugging with PROVE_RCU
Date: Thu, 14 May 2020 09:44:28 -0400 [thread overview]
Message-ID: <ADE40EB3-1B1C-4CCF-9B8A-1F2BC585BCFB@lca.pw> (raw)
In-Reply-To: <20200514133328.GG2869@paulmck-ThinkPad-P72>
> On May 14, 2020, at 9:33 AM, Paul E. McKenney <paulmck@kernel•org> wrote:
>
> On Thu, May 14, 2020 at 08:31:13AM -0400, Qian Cai wrote:
>>
>>
>>> On May 14, 2020, at 8:25 AM, Stephen Rothwell <sfr@canb•auug.org.au> wrote:
>>>
>>> Hi Paul,
>>>
>>> This patch in the rcu tree
>>>
>>> d13fee049fa8 ("Default enable RCU list lockdep debugging with PROVE_RCU")
>>>
>>> is causing whack-a-mole in the syzbot testing of linux-next. Because
>>> they always do a debug build of linux-next, no testing is getting done. :-(
>>>
>>> Can we find another way to find all the bugs that are being discovered
>>> (very slowly)?
>>
>> Alternatively, could syzbot to use PROVE_RCU=n temporarily because it can’t keep up with it? I personally found PROVE_RCU_LIST=y is still useful for my linux-next testing, and don’t want to lose that coverage overnight.
>
> The problem is that PROVE_RCU is exactly PROVE_LOCKING, and asking people
> to test without PROVE_LOCKING is a no-go in my opinion. But of course
> on the other hand if there is no testing of RCU list lockdep debugging,
> those issues will never be found, let alone fixed.
>
> One approach would be to do as Stephen asks (either remove d13fee049fa8
> or pull it out of -next) and have testers force-enable the RCU list
> lockdep debugging.
>
> Would that work for you?
Alternatively, how about having
PROVE_RCU_LIST=n if DEBUG_AID_FOR_SYZBOT
since it is only syzbot can’t keep up with it?
next prev parent reply other threads:[~2020-05-14 13:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-14 12:25 Default enable RCU list lockdep debugging with PROVE_RCU Stephen Rothwell
2020-05-14 12:31 ` Qian Cai
2020-05-14 13:33 ` Paul E. McKenney
2020-05-14 13:39 ` Qian Cai
2020-05-14 13:44 ` Qian Cai [this message]
2020-05-14 13:54 ` Paul E. McKenney
2020-05-14 14:03 ` Qian Cai
2020-05-14 15:34 ` Paul E. McKenney
2020-05-14 15:46 ` Qian Cai
2020-05-14 18:13 ` Paul E. McKenney
2020-05-15 18:36 ` Qian Cai
2020-05-17 21:47 ` Paul E. McKenney
2020-05-18 5:54 ` Rong Chen
2020-05-18 12:44 ` Paul E. McKenney
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