On Tue, Dec 4, 2018 at 4:40 PM Wei Yang <richard.weiyang@xxxxxxxxx> wrote: > > On Tue, Dec 04, 2018 at 04:20:32PM +0800, Pingfan Liu wrote: > >On Tue, Dec 4, 2018 at 3:22 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > >> > >> On Tue 04-12-18 11:05:57, Pingfan Liu wrote: > >> > During my test on some AMD machine, with kexec -l nr_cpus=x option, the > >> > kernel failed to bootup, because some node's data struct can not be allocated, > >> > e.g, on x86, initialized by init_cpu_to_node()->init_memory_less_node(). But > >> > device->numa_node info is used as preferred_nid param for > >> > __alloc_pages_nodemask(), which causes NULL reference > >> > ac->zonelist = node_zonelist(preferred_nid, gfp_mask); > >> > This patch tries to fix the issue by falling back to the first online node, > >> > when encountering such corner case. > >> > >> We have seen similar issues already and the bug was usually that the > >> zonelists were not initialized yet or the node is completely bogus. > >> Zonelists should be initialized by build_all_zonelists quite early so I > >> am wondering whether the later is the case. What is the actual node > >> number the device is associated with? > >> > >The device's node num is 2. And in my case, I used nr_cpus param. Due > >to init_cpu_to_node() initialize all the possible node. It is hard > >for me to figure out without this param, how zonelists is accessed > >before page allocator works. > > If my understanding is correct, we can't do page alloc before zonelist > is initialized. > > I guess Michal's point is to figure out this reason. > Yeah, I know. I just want to emphasize that I hit this bug using nr_cpus, which may be rarely used by people. Hence it may be a different bug as Michal had seen. Sorry for bad English if it cause confusion. Thanks [...]
