Messages in this thread | | | Subject | Re: [PATCH] driver core: ensure a device has valid node id in device_add() | From | Yunsheng Lin <> | Date | Tue, 10 Sep 2019 20:47:40 +0800 |
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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/
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