Messages in this thread | | | Date | Fri, 30 Aug 2019 08:44:21 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] arm64: numa: check the node id before accessing node_to_cpumask_map |
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On Fri 30-08-19 14:35:26, Yunsheng Lin wrote: > On 2019/8/30 13:55, Michal Hocko wrote: > > On Fri 30-08-19 10:26:31, Yunsheng Lin wrote: > >> Some buggy bios may not set the device' numa id, and dev_to_node > >> will return -1, which may cause global-out-of-bounds error > >> detected by KASAN. > > > > Why should we workaround a buggy bios like that? Is it so widespread and > > no BIOS update available? Also, why is this arm64 specific? > > For our case, there is BIOS update available. I just thought it might > be better to protect from this case when BIOS has not implemented the > device' numa id setting feature or the feature from BIOS has some bug. > > It is not arm64 specific, right now I only have arm64 board. If it is > ok to protect this from the buggy BIOS, maybe all other arch can be > changed too.
If we are to really care then this should be consistent among architectures IMHO. But I am not really sure this is really worth it. The code is quite old and I do not really remember any reports.
> >> This patch changes cpumask_of_node to return cpu_none_mask if the > >> node is not valid, and sync the cpumask_of_node between the > >> cpumask_of_node function in numa.h and numa.c. > > > > Why? > > When CONFIG_DEBUG_PER_CPU_MAPS is defined, the cpumask_of_node() in > numa.c is used, if not, the cpumask_of_node() in numa.h is used. > > I am not sure why there is difference between them, and it is there > when since the below commit: > 1a2db300348b ("arm64, numa: Add NUMA support for arm64 platforms.") > > I synced them to keep them consistent whether CONFIG_DEBUG_PER_CPU_MAPS > is defined.
Such a change should be made in a separate patch with a full clarification/justification. From the above it is still not clear why this is needed though.
> >> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> > >> --- > >> arch/arm64/include/asm/numa.h | 6 ++++++ > >> arch/arm64/mm/numa.c | 2 +- > >> 2 files changed, 7 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/arm64/include/asm/numa.h b/arch/arm64/include/asm/numa.h > >> index 626ad01..da891ed 100644 > >> --- a/arch/arm64/include/asm/numa.h > >> +++ b/arch/arm64/include/asm/numa.h > >> @@ -25,6 +25,12 @@ const struct cpumask *cpumask_of_node(int node); > >> /* Returns a pointer to the cpumask of CPUs on Node 'node'. */ > >> static inline const struct cpumask *cpumask_of_node(int node) > >> { > >> + if (node >= nr_node_ids || node < 0) > >> + return cpu_none_mask; > >> + > >> + if (!node_to_cpumask_map[node]) > >> + return cpu_online_mask; > >> + > >> return node_to_cpumask_map[node]; > >> } > >> #endif > >> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c > >> index 4f241cc..3846313 100644 > >> --- a/arch/arm64/mm/numa.c > >> +++ b/arch/arm64/mm/numa.c > >> @@ -46,7 +46,7 @@ EXPORT_SYMBOL(node_to_cpumask_map); > >> */ > >> const struct cpumask *cpumask_of_node(int node) > >> { > >> - if (WARN_ON(node >= nr_node_ids)) > >> + if (WARN_ON(node >= nr_node_ids || node < 0)) > >> return cpu_none_mask; > >> > >> if (WARN_ON(node_to_cpumask_map[node] == NULL)) > >> -- > >> 2.8.1 > >
-- Michal Hocko SUSE Labs
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