* Vlastimil Babka <vbabka@xxxxxxx> [2020-03-17 14:53:26]: > >> > > >> > Mitigate this by allocating the new slab from the node_numa_mem. > >> > >> Are you sure this is really needed and the other 3 patches are not enough for > >> the current SLUB code to work as needed? It seems you are changing the semantics > >> here... > >> > > > > The other 3 patches are not enough because we don't carry the searchnode > > when the actual alloc_pages_node gets called. > > > > With only the 3 patches, we see the above Panic, its signature is slightly > > different from what Sachin first reported and which I have carried in 1st > > patch. > > Ah, I see. So that's the missing pgdat after your series [1] right? Yes the pgdat would be missing after my cpuless, memoryless node patchset. However.. > > That sounds like an argument for Michal's suggestions that pgdats exist and have > correctly populated zonelists for all possible nodes. Only the first patch in this series would be affected by pgdat existing or not. Even if the pgdat existed, the NODE_DATA[nid]->node_present_pages would be 0. Right? So it would look at node_to_mem_node(). And since node 0 is cpuless it would return 0. If we pass this node 0 (which is memoryless/cpuless) to alloc_pages_node. Please note I am only setting node_numa_mem only for offline nodes. However we could change this to set for all offline and memoryless nodes. > node_to_mem_node() could be just a shortcut for the first zone's node in the > zonelist, so that fallback follows the topology. > > [1] > https://lore.kernel.org/linuxppc-dev/20200311110237.5731-1-srikar@xxxxxxxxxxxxxxxxxx/t/#m76e5b4c4084380b1d4b193d5aa0359b987f2290e > -- Thanks and Regards Srikar Dronamraju
