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Date:   Tue, 8 Oct 2019 12:39:07 +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()
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On Tue 08-10-19 06:04:32, Qian Cai wrote:
> 
> 
> > On Oct 8, 2019, at 4:40 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > 
> > Does this tip point to a real deadlock or merely a class of lockdep
> > false dependencies?
> 
> I lean towards it is a real deadlock given how trivial to generate those lock orders everywhere.

Have you actually triggered any real deadlock? With a zone->lock in
place it would be pretty clear with hard lockups detected.

-- 
Michal Hocko
SUSE Labs