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([2600:1000:b029:6649:f4b1:4b94:dfb9:77cf]) by smtp.gmail.com with ESMTPSA id a14sm91508qta.97.2020.01.14.13.40.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Jan 2020 13:40:50 -0800 (PST) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Qian Cai Mime-Version: 1.0 (1.0) Subject: Re: [PATCH -next] mm/hotplug: silence a lockdep splat with printk() Date: Tue, 14 Jan 2020 16:40:49 -0500 Message-Id: References: <20200114210215.GQ19428@dhcp22.suse.cz> Cc: David Hildenbrand , 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 In-Reply-To: <20200114210215.GQ19428@dhcp22.suse.cz> To: Michal Hocko X-Mailer: iPhone Mail (17C54) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Jan 14, 2020, at 4:02 PM, Michal Hocko wrote: >=20 > 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=E2=80=99t know how to convince you, but both random number generator a= nd printk() maintainers agreed to get ride of printk() with zone->lock held a= s you can see in the approved commit mentioned in this patch description bec= ause 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 Andre= w please has a look at this directly?=