Messages in this thread | | | Date | Wed, 30 Oct 2019 11:14:49 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v7] numa: make node_to_cpumask_map() NUMA_NO_NODE aware |
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On Wed, Oct 30, 2019 at 05:34:28PM +0800, Yunsheng Lin wrote: > When passing the return value of dev_to_node() to cpumask_of_node() > without checking if the device's node id is NUMA_NO_NODE, there is > global-out-of-bounds detected by KASAN. > > From the discussion [1], NUMA_NO_NODE really means no node affinity, > which also means all cpus should be usable. So the cpumask_of_node() > should always return all cpus online when user passes the node id as > NUMA_NO_NODE, just like similar semantic that page allocator handles > NUMA_NO_NODE. > > But we cannot really copy the page allocator logic. Simply because the > page allocator doesn't enforce the near node affinity. It just picks it > up as a preferred node but then it is free to fallback to any other numa > node. This is not the case here and node_to_cpumask_map will only restrict > to the particular node's cpus which would have really non deterministic > behavior depending on where the code is executed. So in fact we really > want to return cpu_online_mask for NUMA_NO_NODE. > > Also there is a debugging version of node_to_cpumask_map() for x86 and > arm64, which is only used when CONFIG_DEBUG_PER_CPU_MAPS is defined, this > patch changes it to handle NUMA_NO_NODE as normal node_to_cpumask_map(). > > [1] https://lkml.org/lkml/2019/9/11/66 > Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> > Suggested-by: Michal Hocko <mhocko@kernel.org> > Acked-by: Michal Hocko <mhocko@suse.com> > Acked-by: Paul Burton <paul.burton@mips.com> # MIPS bits
Still:
Nacked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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