From: Yunsheng Lin <linyunsheng@huawei.com>
To: Greg KH <gregkh@linuxfoundation.org>, Michal Hocko <mhocko@kernel.org>
Cc: <rafael@kernel.org>, <linux-kernel@vger.kernel.org>,
<peterz@infradead.org>, <mingo@kernel.org>, <linuxarm@huawei.com>
Subject: Re: [PATCH] driver core: ensure a device has valid node id in device_add()
Date: Tue, 10 Sep 2019 20:47:40 +0800 [thread overview]
Message-ID: <5a5645d2-030f-7921-432f-ff7d657405b8@huawei.com> (raw)
In-Reply-To: <20190910111252.GA8970@kroah.com>
On 2019/9/10 19:12, Greg KH wrote:
> On Tue, Sep 10, 2019 at 01:04:51PM +0200, Michal Hocko wrote:
>> On Tue 10-09-19 18:58:05, Yunsheng Lin wrote:
>>> On 2019/9/10 17:31, Greg KH wrote:
>>>> On Tue, Sep 10, 2019 at 02:43:32PM +0800, Yunsheng Lin wrote:
>>>>> On 2019/9/9 17:53, Greg KH wrote:
>>>>>> On Mon, Sep 09, 2019 at 02:04:23PM +0800, Yunsheng Lin wrote:
>>>>>>> Currently a device does not belong to any of the numa nodes
>>>>>>> (dev->numa_node is NUMA_NO_NODE) when the node id is neither
>>>>>>> specified by fw nor by virtual device layer and the device has
>>>>>>> no parent device.
>>>>>>
>>>>>> Is this really a problem?
>>>>>
>>>>> Not really.
>>>>> Someone need to guess the node id when it is not specified, right?
>>>>
>>>> No, why? Guessing guarantees you will get it wrong on some systems.
>>>>
>>>> Are you seeing real problems because the id is not being set? What
>>>> problem is this fixing that you can actually observe?
>>>
>>> When passing the return value of dev_to_node() to cpumask_of_node()
>>> without checking the node id if the node id is not valid, there is
>>> global-out-of-bounds detected by KASAN as below:
>>
>> OK, I seem to remember this being brought up already. And now when I
>> think about it, we really want to make cpumask_of_node NUMA_NO_NODE
>> aware. That means using the same trick the allocator does for this
>> special case.
>
> That seems reasonable to me, and much more "obvious" as to what is going
> on.
>
Ok, thanks for the suggestion.
For arm64 and x86, there are two versions of cpumask_of_node().
when CONFIG_DEBUG_PER_CPU_MAPS is defined, the cpumask_of_node()
in arch/x86/mm/numa.c is used, which does partial node id checking:
const struct cpumask *cpumask_of_node(int node)
{
if (node >= nr_node_ids) {
printk(KERN_WARNING
"cpumask_of_node(%d): node > nr_node_ids(%u)\n",
node, nr_node_ids);
dump_stack();
return cpu_none_mask;
}
if (node_to_cpumask_map[node] == NULL) {
printk(KERN_WARNING
"cpumask_of_node(%d): no node_to_cpumask_map!\n",
node);
dump_stack();
return cpu_online_mask;
}
return node_to_cpumask_map[node];
}
when CONFIG_DEBUG_PER_CPU_MAPS is undefined, the cpumask_of_node()
in arch/x86/include/asm/topology.h is used:
static inline const struct cpumask *cpumask_of_node(int node)
{
return node_to_cpumask_map[node];
}
As discussion in [1], adding the checking in cpumask_of_node() with
CONFIG_DEBUG_PER_CPU_MAPS not defined increases overhead for everyone,
and it is already true that cpumask_of_node() requires a valid node_id.
So maybe the overhead is worth it?
Hi, Peter
Does the argument in this thread about making cpumask_of_node()
NUMA_NO_NODE aware make sense to you?
[1] https://lore.kernel.org/patchwork/patch/1122516/
next prev parent reply other threads:[~2019-09-10 12:49 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 6:04 [PATCH] driver core: ensure a device has valid node id in device_add() Yunsheng Lin
2019-09-09 9:53 ` Greg KH
2019-09-10 6:43 ` Yunsheng Lin
2019-09-10 7:13 ` Michal Hocko
2019-09-10 9:31 ` Greg KH
2019-09-10 10:58 ` Yunsheng Lin
2019-09-10 11:04 ` Michal Hocko
2019-09-10 11:12 ` Greg KH
2019-09-10 12:47 ` Yunsheng Lin [this message]
2019-09-10 12:53 ` Michal Hocko
2019-09-11 5:33 ` Michal Hocko
2019-09-11 6:15 ` Yunsheng Lin
2019-09-11 6:49 ` Michal Hocko
2019-09-11 7:22 ` Yunsheng Lin
2019-09-11 7:34 ` Michal Hocko
2019-09-11 11:03 ` Yunsheng Lin
2019-09-11 11:41 ` Yunsheng Lin
2019-09-11 12:02 ` Michal Hocko
2019-09-23 15:09 ` Peter Zijlstra
2019-09-09 18:50 ` Michal Hocko
2019-09-10 7:08 ` Yunsheng Lin
2019-09-10 7:24 ` Michal Hocko
2019-09-10 10:40 ` Yunsheng Lin
2019-09-10 11:01 ` Michal Hocko
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