From: Peter Zijlstra <peterz@infradead•org>
To: Yunsheng Lin <linyunsheng@huawei•com>
Cc: dalias@libc•org, linux-sh@vger•kernel.org,
catalin.marinas@arm•com, dave.hansen@linux•intel.com,
heiko.carstens@de•ibm.com, linuxarm@huawei•com,
jiaxun.yang@flygoat•com, linux-mips@vger•kernel.org,
mwb@linux•vnet.ibm.com, paulus@samba•org, hpa@zytor•com,
sparclinux@vger•kernel.org, chenhc@lemote•com, will@kernel•org,
bp@alien8•de, linux-s390@vger•kernel.org,
ysato@users•sourceforge.jp, x86@kernel•org, rppt@linux•ibm.com,
borntraeger@de•ibm.com, dledford@redhat•com, mingo@redhat•com,
jeffrey.t.kirsher@intel•com, jhogan@kernel•org,
nfont@linux•vnet.ibm.com, mattst88@gmail•com,
len.brown@intel•com, gor@linux•ibm.com,
anshuman.khandual@arm•com,
Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
ink@jurassic•park.msu.ru, luto@kernel•org, tglx@linutronix•de,
naveen.n.rao@linux•vnet.ibm.com,
linux-arm-kernel@lists•infradead.org, rth@twiddle•net,
axboe@kernel•dk, linuxppc-dev@lists•ozlabs.org,
"Rafael J. Wysocki" <rjw@rjwysocki•net>,
linux-kernel@vger•kernel.org, ralf@linux-mips•org,
tbogendoerfer@suse•de, paul.burton@mips•com,
linux-alpha@vger•kernel.org, cai@lca•pw,
akpm@linux-foundation•org, robin.murphy@arm•com,
davem@davemloft•net
Subject: Re: [PATCH v2 2/9] x86: numa: check the node id consistently for x86
Date: Tue, 3 Sep 2019 09:11:11 +0200 [thread overview]
Message-ID: <20190903071111.GU2369@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1f48081c-c9d6-8f3e-9559-8b0bec98f125@huawei.com>
On Tue, Sep 03, 2019 at 02:19:04PM +0800, Yunsheng Lin wrote:
> On 2019/9/2 20:56, Peter Zijlstra wrote:
> > On Mon, Sep 02, 2019 at 08:25:24PM +0800, Yunsheng Lin wrote:
> >> On 2019/9/2 15:25, Peter Zijlstra wrote:
> >>> On Mon, Sep 02, 2019 at 01:46:51PM +0800, Yunsheng Lin wrote:
> >>>> On 2019/9/1 0:12, Peter Zijlstra wrote:
> >>>
> >>>>> 1) because even it is not set, the device really does belong to a node.
> >>>>> It is impossible a device will have magic uniform access to memory when
> >>>>> CPUs cannot.
> >>>>
> >>>> So it means dev_to_node() will return either NUMA_NO_NODE or a
> >>>> valid node id?
> >>>
> >>> NUMA_NO_NODE := -1, which is not a valid node number. It is also, like I
> >>> said, not a valid device location on a NUMA system.
> >>>
> >>> Just because ACPI/BIOS is shit, doesn't mean the device doesn't have a
> >>> node association. It just means we don't know and might have to guess.
> >>
> >> How do we guess the device's location when ACPI/BIOS does not set it?
> >
> > See device_add(), it looks to the device's parent and on NO_NODE, puts
> > it there.
> >
> > Lacking any hints, just stick it to node0 and print a FW_BUG or
> > something.
> >
> >> It seems dev_to_node() does not do anything about that and leave the
> >> job to the caller or whatever function that get called with its return
> >> value, such as cpumask_of_node().
> >
> > Well, dev_to_node() doesn't do anything; nor should it. It are the
> > callers of set_dev_node() that should be taking care.
> >
> > Also note how device_add() sets the device node to the parent device's
> > node on NUMA_NO_NODE. Arguably we should change it to complain when it
> > finds NUMA_NO_NODE and !parent.
>
> Is it possible that the node id set by device_add() become invalid
> if the node is offlined, then dev_to_node() may return a invalid
> node id.
In that case I would expect the device to go away too. Once the memory
controller goes away, the PCI bus connected to it cannot continue to
function.
> From the comment in select_fallback_rq(), it seems that a node can
> be offlined, not sure if node offline process has taken cared of that?
>
> /*
> * If the node that the CPU is on has been offlined, cpu_to_node()
> * will return -1. There is no CPU on the node, and we should
> * select the CPU on the other node.
> */
Ugh, so I disagree with that notion. cpu_to_node() mapping should be
fixed, you simply cannot change it after boot, too much stuff relies on
it.
Setting cpu_to_node to -1 on node offline is just wrong. But alas, it
seems this is already so.
> With the above assumption that a device is always on a valid node,
> the node id returned from dev_to_node() can be safely passed to
> cpumask_of_node() without any checking?
next prev parent reply other threads:[~2019-09-03 7:14 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-31 5:58 [PATCH v2 0/9] check the node id consistently across different arches Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 1/9] arm64: numa: check the node id consistently for arm64 Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 2/9] x86: numa: check the node id consistently for x86 Yunsheng Lin
2019-08-31 8:55 ` Peter Zijlstra
2019-08-31 10:09 ` Yunsheng Lin
2019-08-31 16:12 ` Peter Zijlstra
2019-09-02 5:46 ` Yunsheng Lin
2019-09-02 7:25 ` Peter Zijlstra
2019-09-02 12:25 ` Yunsheng Lin
2019-09-02 12:56 ` Peter Zijlstra
2019-09-02 18:22 ` Ingo Molnar
2019-09-02 19:14 ` Peter Zijlstra
2019-09-03 6:19 ` Yunsheng Lin
2019-09-03 7:11 ` Peter Zijlstra [this message]
2019-09-03 8:31 ` Yunsheng Lin
2019-09-03 12:15 ` Salil Mehta
2019-09-03 14:28 ` Peter Zijlstra
2019-09-02 18:17 ` Ingo Molnar
2019-09-03 7:53 ` [PATCH] x86/mm: Fix cpumask_of_node() error condition Peter Zijlstra
2019-08-31 5:58 ` [PATCH v2 3/9] alpha: numa: check the node id consistently for alpha Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 4/9] powerpc: numa: check the node id consistently for powerpc Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 5/9] s390: numa: check the node id consistently for s390 Yunsheng Lin
2019-09-02 4:05 ` kbuild test robot
2019-08-31 5:58 ` [PATCH v2 6/9] sh: numa: check the node id consistently for sh Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 7/9] sparc64: numa: check the node id consistently for sparc64 Yunsheng Lin
2019-08-31 6:53 ` David Miller
2019-08-31 8:57 ` Yunsheng Lin
2019-08-31 20:02 ` David Miller
2019-09-02 6:08 ` Yunsheng Lin
2019-09-02 15:17 ` David Miller
2019-08-31 5:58 ` [PATCH v2 8/9] mips: numa: check the node id consistently for mips ip27 Yunsheng Lin
2019-08-31 15:45 ` Paul Burton
2019-09-02 6:11 ` Yunsheng Lin
2019-08-31 5:58 ` [PATCH v2 9/9] mips: numa: check the node id consistently for mips loongson64 Yunsheng Lin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190903071111.GU2369@hirez.programming.kicks-ass.net \
--to=peterz@infradead$(echo .)org \
--cc=akpm@linux-foundation$(echo .)org \
--cc=anshuman.khandual@arm$(echo .)com \
--cc=axboe@kernel$(echo .)dk \
--cc=borntraeger@de$(echo .)ibm.com \
--cc=bp@alien8$(echo .)de \
--cc=cai@lca$(echo .)pw \
--cc=catalin.marinas@arm$(echo .)com \
--cc=chenhc@lemote$(echo .)com \
--cc=dalias@libc$(echo .)org \
--cc=dave.hansen@linux$(echo .)intel.com \
--cc=davem@davemloft$(echo .)net \
--cc=dledford@redhat$(echo .)com \
--cc=gor@linux$(echo .)ibm.com \
--cc=gregkh@linuxfoundation$(echo .)org \
--cc=heiko.carstens@de$(echo .)ibm.com \
--cc=hpa@zytor$(echo .)com \
--cc=ink@jurassic$(echo .)park.msu.ru \
--cc=jeffrey.t.kirsher@intel$(echo .)com \
--cc=jhogan@kernel$(echo .)org \
--cc=jiaxun.yang@flygoat$(echo .)com \
--cc=len.brown@intel$(echo .)com \
--cc=linux-alpha@vger$(echo .)kernel.org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=linux-mips@vger$(echo .)kernel.org \
--cc=linux-s390@vger$(echo .)kernel.org \
--cc=linux-sh@vger$(echo .)kernel.org \
--cc=linuxarm@huawei$(echo .)com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=linyunsheng@huawei$(echo .)com \
--cc=luto@kernel$(echo .)org \
--cc=mattst88@gmail$(echo .)com \
--cc=mingo@redhat$(echo .)com \
--cc=mwb@linux$(echo .)vnet.ibm.com \
--cc=naveen.n.rao@linux$(echo .)vnet.ibm.com \
--cc=nfont@linux$(echo .)vnet.ibm.com \
--cc=paul.burton@mips$(echo .)com \
--cc=paulus@samba$(echo .)org \
--cc=ralf@linux-mips$(echo .)org \
--cc=rjw@rjwysocki$(echo .)net \
--cc=robin.murphy@arm$(echo .)com \
--cc=rppt@linux$(echo .)ibm.com \
--cc=rth@twiddle$(echo .)net \
--cc=sparclinux@vger$(echo .)kernel.org \
--cc=tbogendoerfer@suse$(echo .)de \
--cc=tglx@linutronix$(echo .)de \
--cc=will@kernel$(echo .)org \
--cc=x86@kernel$(echo .)org \
--cc=ysato@users$(echo .)sourceforge.jp \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox