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Date:   Tue, 8 Oct 2019 14:39:20 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Qian Cai <cai@lca.pw>
Cc:     Petr Mladek <pmladek@suse.com>, akpm@linux-foundation.org,
        sergey.senozhatsky.work@gmail.com, rostedt@goodmis.org,
        peterz@infradead.org, linux-mm@kvack.org,
        john.ogness@linutronix.de, david@redhat.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm/page_isolation: fix a deadlock with printk()
Message-ID: <20191008123920.GI6681@dhcp22.suse.cz>
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On Tue 08-10-19 08:00:43, Qian Cai wrote:
> 
> 
> > On Oct 8, 2019, at 6:39 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > 
> > Have you actually triggered any real deadlock? With a zone->lock in
> > place it would be pretty clear with hard lockups detected.
> 
> Yes, I did trigger here and there, and those lockdep splats are
> especially useful to figure out why.

Can you provide a lockdep splat from an actual deadlock please? I am
sorry but your responses tend to be really cryptic and I never know when
you are talking about actual deadlocks and lockdep splats. I have asked
about the former several times never receiving a specific answer.
-- 
Michal Hocko
SUSE Labs