From: Yunsheng Lin <linyunsheng@huawei.com>
To: Peter Zijlstra <peterz@infradead.org>
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 14:19:04 +0800 [thread overview]
Message-ID: <1f48081c-c9d6-8f3e-9559-8b0bec98f125@huawei.com> (raw)
In-Reply-To: <20190902125644.GQ2369@hirez.programming.kicks-ass.net>
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.
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.
*/
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?
>
> ---
> drivers/base/core.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index f0dd8e38fee3..2caf204966a0 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -2120,8 +2120,16 @@ int device_add(struct device *dev)
> dev->kobj.parent = kobj;
>
> /* use parent numa_node */
> - if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
> - set_dev_node(dev, dev_to_node(parent));
> + if (dev_to_node(dev) == NUMA_NO_NODE) {
> + if (parent)
> + set_dev_node(dev, dev_to_node(parent));
> +#ifdef CONFIG_NUMA
> + else {
> + pr_err("device: '%s': has no assigned NUMA node\n", dev_name(dev));
> + set_dev_node(dev, 0);
> + }
> +#endif
> + }
>
> /* first, register with generic layer. */
> /* we require the name to be set before, and pass NULL */
>
> .
>
next prev parent reply other threads:[~2019-09-03 6:23 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 [this message]
2019-09-03 7:11 ` Peter Zijlstra
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
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