On 2019/9/22 6:38, Paul Burton wrote: > Hi Yunsheng, > > On Tue, Sep 17, 2019 at 08:48:54PM +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://lore.kernel.org/patchwork/patch/1125789/ >> Signed-off-by: Yunsheng Lin <linyunsh...@huawei.com> >> Suggested-by: Michal Hocko <mho...@kernel.org> >> Acked-by: Michal Hocko <mho...@suse.com> > > If you end up sending another revision then I think it would be worth > replacing -1 with NUMA_NO_NODE in > arch/mips/include/asm/mach-ip27/topology.h for consistency, but in any > case:
Perhaps it is better to replace -1 with NUMA_NO_NODE along with cpu_all_mask -> cpu_online_mask change if the cpu_all_mask -> cpu_online_mask change is reasonable. Anyway, will do that if there is another version needed. > > Acked-by: Paul Burton <paul.bur...@mips.com> # MIPS bits Thanks for that. > > Thanks, > Paul > >> --- >> V6: Drop the cpu_all_mask -> cpu_online_mask change for it seems a >> little controversial, may need deeper investigation, and rebased >> on the latest linux-next. >> V5: Drop unsigned "fix" change for x86/arm64, and change comment log >> according to Michal's comment. >> V4: Have all these changes in a single patch. >> V3: Change to only handle NUMA_NO_NODE, and return cpu_online_mask >> for NUMA_NO_NODE case, and change the commit log to better justify >> the change. >> V2: make the node id checking change to other arches too. >> --- >> arch/arm64/include/asm/numa.h | 3 +++ >> arch/arm64/mm/numa.c | 3 +++ >> arch/mips/include/asm/mach-loongson64/topology.h | 4 +++- >> arch/s390/include/asm/topology.h | 3 +++ >> arch/x86/include/asm/topology.h | 3 +++ >> arch/x86/mm/numa.c | 3 +++ >> 6 files changed, 18 insertions(+), 1 deletion(-) > > . >