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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id 4sm8221361qkv.44.2020.01.15.03.49.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Jan 2020 03:49:05 -0800 (PST) Content-Type: multipart/alternative; boundary=Apple-Mail-C1316F67-430D-4F9A-8F97-1AE13B7F595C Content-Transfer-Encoding: 7bit From: Qian Cai Mime-Version: 1.0 (1.0) Subject: Re: [PATCH -next] mm/hotplug: silence a lockdep splat with printk() Date: Wed, 15 Jan 2020 06:49:03 -0500 Message-Id: References: <20200115095253.36e5iqn77n4exj3s@pathway.suse.cz> Cc: Michal Hocko , David Hildenbrand , akpm@linux-foundation.org, sergey.senozhatsky.work@gmail.com, rostedt@goodmis.org, peterz@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: <20200115095253.36e5iqn77n4exj3s@pathway.suse.cz> To: Petr Mladek X-Mailer: iPhone Mail (17C54) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --Apple-Mail-C1316F67-430D-4F9A-8F97-1AE13B7F595C Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable > On Jan 15, 2020, at 4:52 AM, Petr Mladek wrote: >=20 > I could understand that Michal is against hack in -mm code that > would just hide a false positive warning. Well, I don=E2=80=99t have any confidence to say everything this patch is tr= ying to fix is false positives. I have been spent the last a few months to r= esearch this, so I don=E2=80=99t feel like to do this again. https://lore.kernel.org/linux-mm/1570633715.5937.10.camel@lca.pw/ >=20 > If you really need a solution before the console offload gets > upstream then I suggest to do something really simple. For example, > disable lockdep around the allocation in console registration code > that is proven to produce the false positive chain. --Apple-Mail-C1316F67-430D-4F9A-8F97-1AE13B7F595C Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable


On Jan 15, 2020, at 4:52 AM, Petr Mladek <= pmladek@suse.com> wrote:

I could understand that Michal is against hack in= -mm code that
would just hide a false positive warning.

Well, I don=E2=80=99t have any= confidence to say everything this patch is trying to fix is false positives= . I have been spent the last a few months to research this, so I don=E2=80=99= t feel like to do this again.



If you really need a solut= ion before the console offload gets
upstream then I suggest t= o do something really simple. For example,
disable lockdep a= round the allocation in console registration code
that is pr= oven to produce the false positive chain.
= --Apple-Mail-C1316F67-430D-4F9A-8F97-1AE13B7F595C--