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From: Michal Hocko <mhocko@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Yunsheng Lin <linyunsheng@huawei.com>,
	catalin.marinas@arm.com, will@kernel.org, mingo@redhat.com,
	bp@alien8.de, rth@twiddle.net, ink@jurassic.park.msu.ru,
	mattst88@gmail.com, benh@kernel.crashing.org, paulus@samba.org,
	mpe@ellerman.id.au, heiko.carstens@de.ibm.com, gor@linux.ibm.com,
	borntraeger@de.ibm.com, ysato@users.sourceforge.jp,
	dalias@libc.org, davem@davemloft.net, ralf@linux-mips.org,
	paul.burton@mips.com, jhogan@kernel.org, jiaxun.yang@flygoat.com,
	chenhc@lemote.com, akpm@linux-foundation.org, rppt@linux.ibm.com,
	anshuman.khandual@arm.com, tglx@linutronix.de, cai@lca.pw,
	robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, hpa@zytor.com, x86@kernel.org,
	dave.hansen@linux.intel.com, luto@kernel.org,
	len.brown@intel.com, axboe@kernel.dk, dledford@redhat.com,
	jeffrey.t.kirsher@intel.com, linux-alpha@vger.kernel.org,
	naveen.n.rao@linux.vnet.ibm.com, mwb@linux.vnet.ibm.com,
	linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
	linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
	tbogendoerfer@suse.de, linux-mips@vger.kernel.org,
	rafael@kernel.org, gregkh@linuxfoundation.org
Subject: Re: [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware
Date: Wed, 25 Sep 2019 15:25:44 +0200	[thread overview]
Message-ID: <20190925132544.GL23050@dhcp22.suse.cz> (raw)
In-Reply-To: <20190925104040.GD4553@hirez.programming.kicks-ass.net>

On Wed 25-09-19 12:40:40, Peter Zijlstra wrote:
> On Tue, Sep 24, 2019 at 03:19:39PM +0200, Michal Hocko wrote:
> 
> > > The below would get rid of the PMU and workqueue warnings with no
> > > side-effects (the device isn't used for anything except sysfs).
> > 
> > Hardcoding to 0 is simply wrong, if the node0 is cpuless for example...
> 
> It doesn't matter.... that 0 is _never_ used. These are fake devices,
> and all we care about is getting rid of that error.

That is a very subtle and hard to review assumption. Even if this holds
now a future change might easily break this AFAIU. It also assumes that
you catch all such special devices.

I am sorry but I still do not understand why you consider this whack a
mole better then simply live with the fact that NUMA_NO_NODE is a
reality and that using the full cpu mask is a reasonable answer to that.
Anyway, I feel we are loop here so I will leave out the final decision
to you.

> If it makes you feel better we can make it -2 and have dev_to_node()
> WARN if it ever sees one.

That would help

-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2019-09-25 13:25 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-17 12:48 [PATCH v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Yunsheng Lin
2019-09-23 15:15 ` Peter Zijlstra
2019-09-23 15:28   ` Michal Hocko
2019-09-23 15:48     ` Peter Zijlstra
2019-09-23 16:52       ` Michal Hocko
2019-09-23 20:34         ` Peter Zijlstra
2019-09-24  1:29           ` Yunsheng Lin
2019-09-24  9:25             ` Peter Zijlstra
2019-09-24 11:07               ` Yunsheng Lin
2019-09-24 11:28                 ` Peter Zijlstra
2019-09-24 11:44                   ` Yunsheng Lin
2019-09-24 11:58                     ` Peter Zijlstra
2019-09-24 12:09                       ` Yunsheng Lin
2019-09-24  7:47           ` Michal Hocko
2019-09-24  9:17             ` Peter Zijlstra
2019-09-24 10:56               ` Michal Hocko
2019-09-24 11:23                 ` Peter Zijlstra
2019-09-24 11:54                   ` Michal Hocko
2019-09-24 12:09                     ` Peter Zijlstra
2019-09-24 12:25                       ` Michal Hocko
2019-09-24 12:43                         ` Peter Zijlstra
2019-09-24 12:59                           ` Peter Zijlstra
2019-09-24 13:19                             ` Michal Hocko
2019-09-25  9:14                               ` Yunsheng Lin
2019-09-25 10:41                                 ` Peter Zijlstra
2019-10-08  8:38                                   ` Yunsheng Lin
2019-10-09 12:25                                     ` Robin Murphy
2019-10-10  6:07                                       ` Yunsheng Lin
2019-10-10  7:32                                         ` Michal Hocko
2019-10-11  3:27                                           ` Yunsheng Lin
2019-10-11 11:15                                             ` Peter Zijlstra
2019-10-12  6:17                                               ` Yunsheng Lin
2019-10-12  7:40                                                 ` Greg KH
2019-10-12  9:47                                                   ` Yunsheng Lin
2019-10-12 10:40                                                     ` Greg KH
2019-10-12 10:47                                                       ` Greg KH
2019-10-14  8:00                                                         ` Yunsheng Lin
2019-10-14  9:25                                                           ` Greg KH
2019-10-14  9:49                                                             ` Peter Zijlstra
2019-10-14 10:04                                                               ` Greg KH
2019-10-15 10:40                                                             ` Yunsheng Lin
2019-10-15 16:58                                                               ` Greg KH
2019-10-16 12:07                                                                 ` Yunsheng Lin
2019-10-28  9:20                                                   ` Yunsheng Lin
2019-10-29  8:53                                                     ` Michal Hocko
2019-10-30  1:58                                                       ` Yunsheng Lin
2019-10-10  8:56                                       ` Peter Zijlstra
2019-09-25 10:40                               ` Peter Zijlstra
2019-09-25 13:25                                 ` Michal Hocko [this message]
2019-09-25 16:31                                   ` Peter Zijlstra
2019-09-25 21:45                                     ` Peter Zijlstra
2019-09-26  9:05                                       ` Peter Zijlstra
2019-09-26 12:10                                         ` Peter Zijlstra

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