Hi, On Thu, Sep 12, 2019 at 06:15:33PM +0800, Yunsheng Lin wrote: > When passing the return value of dev_to_node() to cpumask_of_node() > without checking the node id if the 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. > > Since this arch was already NUMA_NO_NODE aware, this patch only changes > it to return cpu_online_mask and use NUMA_NO_NODE instead of "-1". > > [1] https://lore.kernel.org/patchwork/patch/1125789/ > Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx> > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> > --- > 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. > --- > arch/mips/include/asm/mach-ip27/topology.h | 4 ++-- Nit: the subject says "mips:", but this patch only touches sgi-ip27 and loongson is updated as a separate patch. I don't see why both patches cannot be merged. Moreover, the whole set can be made as a single patch, IMHO. > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/mips/include/asm/mach-ip27/topology.h b/arch/mips/include/asm/mach-ip27/topology.h > index 965f079..04505e6 100644 > --- a/arch/mips/include/asm/mach-ip27/topology.h > +++ b/arch/mips/include/asm/mach-ip27/topology.h > @@ -15,8 +15,8 @@ struct cpuinfo_ip27 { > extern struct cpuinfo_ip27 sn_cpu_info[NR_CPUS]; > > #define cpu_to_node(cpu) (sn_cpu_info[(cpu)].p_nodeid) > -#define cpumask_of_node(node) ((node) == -1 ? \ > - cpu_all_mask : \ > +#define cpumask_of_node(node) ((node) == NUMA_NO_NODE ? \ > + cpu_online_mask : \ > &hub_data(node)->h_cpus) > struct pci_bus; > extern int pcibus_to_node(struct pci_bus *); > -- > 2.8.1 > -- Sincerely yours, Mike.
