From: Qian Cai <cai@lca.pw>
To: Michal Hocko <mhocko@kernel.org>
Cc: David Hildenbrand <david@redhat.com>,
akpm@linux-foundation.org, sergey.senozhatsky.work@gmail.com,
pmladek@suse.com, rostedt@goodmis.org, peterz@infradead.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next] mm/hotplug: silence a lockdep splat with printk()
Date: Tue, 14 Jan 2020 16:40:49 -0500 [thread overview]
Message-ID: <D5CC7C52-1F08-401E-BDCA-DF617909BB9D@lca.pw> (raw)
In-Reply-To: <20200114210215.GQ19428@dhcp22.suse.cz>
> On Jan 14, 2020, at 4:02 PM, Michal Hocko <mhocko@kernel.org> wrote:
>
> Yeah, that was a long discussion with a lot of lockdep false positives.
> I believe I have made it clear that the console code shouldn't depend on
> memory allocation because that is just too fragile. If that is not
> possible for some reason then it has to be mentioned in the changelog.
> I really do not want us to add kludges to the MM code just because of
> printk deficiencies unless that is absolutely inevitable.
I don’t know how to convince you, but both random number generator and printk() maintainers agreed to get ride of printk() with zone->lock held as you can see in the approved commit mentioned in this patch description because it is a whac-a-mole to fix other places. In other word, the patch alone fixes quite a few false positives and potential real deadlocks. Maybe Andrew please has a look at this directly?
next prev parent reply other threads:[~2020-01-14 21:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 20:11 [PATCH -next] mm/hotplug: silence a lockdep splat with printk() Qian Cai
2020-01-14 20:20 ` David Hildenbrand
2020-01-14 21:02 ` Michal Hocko
2020-01-14 21:40 ` Qian Cai [this message]
2020-01-14 23:53 ` Andrew Morton
2020-01-15 1:02 ` Qian Cai
2020-01-15 1:19 ` Andrew Morton
2020-01-15 1:38 ` Qian Cai
2020-01-15 8:37 ` Michal Hocko
2020-01-15 9:52 ` Petr Mladek
2020-01-15 11:49 ` Qian Cai
2020-01-15 17:02 ` Petr Mladek
2020-01-15 17:16 ` Qian Cai
2020-01-16 14:29 ` Petr Mladek
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