Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 21 Jun 2021 15:28:53 +0800
From:   Boqun Feng <boqun.feng@gmail.com>
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] Fix issues in check_irq_usage()
Message-ID: <YNA/tdi4Dh4FLC16@boqun-archlinux>
References: <20210618170110.3699115-1-boqun.feng@gmail.com>
 <2760706369e7401dd794339e3f22859c243272ea.camel@sipsolutions.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <2760706369e7401dd794339e3f22859c243272ea.camel@sipsolutions.net>
Precedence: bulk

On Fri, Jun 18, 2021 at 07:36:26PM +0200, Johannes Berg wrote:
> Hi Boqun,
> 

Hello,

> Great, thanks! I'll ask the folks who could reproduce this issue to do
> so as soon as possible.
> 
> Not sure if you saw my previous posting:
> https://lore.kernel.org/lkml/8a61ecda99843307018e3e71a5540682436443fc.camel@sipsolutions.net/T/#u
> 

I just replied that thread on the particular deadlock scenario there.

> That was with patch 3 of this set already applied.
> 
> 
> If I understand correctly, then you're basically saying that if we apply
> all the 3 (or 4) patches here, it'll just change the report (that you
> can see at the link above) to actually say something that I can
> understand to see where the issue is?
> 

Sort of, these patches will provide you a correct lock dependency path
on the deadlock possibility along with the correct call stacks. However,
currently I don't think it's easy for lockdep to print the 4-CPU
scenario that I post in the other email, so it will still take some
effort to decode the lockdep, so you will still need some lockdep
knowledge to understand the real issue ;-(

Regards,
Boqun

> Thanks,
> johannes
> 
>