| Message ID | 20220623125442.645240-1-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [1/2] powerpc/numa: Return the first online node instead of 0 | expand |
* Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [2022-06-23 18:24:41]: > If early cpu to node mapping finds an invalid node id, return > the first online node instead of node 0. > > With commit e75130f20b1f ("powerpc/numa: Offline memoryless cpuless node 0") > the kernel marks node 0 offline in certain scenarios. > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > arch/powerpc/include/asm/topology.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h > index 8a4d4f4d9749..704088b1d53c 100644 > --- a/arch/powerpc/include/asm/topology.h > +++ b/arch/powerpc/include/asm/topology.h > @@ -60,7 +60,7 @@ static inline int early_cpu_to_node(int cpu) > * Fall back to node 0 if nid is unset (it should be, except bugs). > * This allows callers to safely do NODE_DATA(early_cpu_to_node(cpu)). > */ > - return (nid < 0) ? 0 : nid; > + return (nid < 0) ? first_online_node : nid; Looks good but just two queries. 1. Is there a possibility of early_cpu_to_node() being called before any node is online? 2. first_online_node is actually not a variable, it returns the lowest online node. Right? If lets a early_cpu_to_node() for the same CPU across a node online/offline may end up giving two different nids. Right? > } > > int of_drconf_to_nid_single(struct drmem_lmb *lmb); > -- > 2.36.1 >
Srikar Dronamraju <srikar@linux.vnet.ibm.com> writes: > * Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [2022-06-23 18:24:41]: > >> If early cpu to node mapping finds an invalid node id, return >> the first online node instead of node 0. >> >> With commit e75130f20b1f ("powerpc/numa: Offline memoryless cpuless node 0") >> the kernel marks node 0 offline in certain scenarios. >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> --- >> arch/powerpc/include/asm/topology.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h >> index 8a4d4f4d9749..704088b1d53c 100644 >> --- a/arch/powerpc/include/asm/topology.h >> +++ b/arch/powerpc/include/asm/topology.h >> @@ -60,7 +60,7 @@ static inline int early_cpu_to_node(int cpu) >> * Fall back to node 0 if nid is unset (it should be, except bugs). >> * This allows callers to safely do NODE_DATA(early_cpu_to_node(cpu)). >> */ >> - return (nid < 0) ? 0 : nid; >> + return (nid < 0) ? first_online_node : nid; > > Looks good but just two queries. > > 1. Is there a possibility of early_cpu_to_node() being called before any > node is online? The kernel operate with node 0 online most of the early boot and mark it offline in mem_topology_setup() just before parse_numa_properties(). So we should find some nodes set online. > > 2. first_online_node is actually not a variable, it returns the lowest > online node. Right? If lets a early_cpu_to_node() for the same CPU across a > node online/offline may end up giving two different nids. Right? > The change is specific to a case where we find uninitialized numa_cpu_lookup_table. ie, the firmware didn't specify the mapping for the cpu. I do agree that for such cpus the node mapping can change because of the above. I am not sure whether this can cause any issue in practice. But returning node 0 which can be marked offline can result in crashes? > >> } >> >> int of_drconf_to_nid_single(struct drmem_lmb *lmb); >> -- >> 2.36.1 >> > > -- > Thanks and Regards > Srikar Dronamraju
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h index 8a4d4f4d9749..704088b1d53c 100644 --- a/arch/powerpc/include/asm/topology.h +++ b/arch/powerpc/include/asm/topology.h @@ -60,7 +60,7 @@ static inline int early_cpu_to_node(int cpu) * Fall back to node 0 if nid is unset (it should be, except bugs). * This allows callers to safely do NODE_DATA(early_cpu_to_node(cpu)). */ - return (nid < 0) ? 0 : nid; + return (nid < 0) ? first_online_node : nid; } int of_drconf_to_nid_single(struct drmem_lmb *lmb);
If early cpu to node mapping finds an invalid node id, return the first online node instead of node 0. With commit e75130f20b1f ("powerpc/numa: Offline memoryless cpuless node 0") the kernel marks node 0 offline in certain scenarios. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> --- arch/powerpc/include/asm/topology.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)