On Wed 05-12-18 17:29:31, Pingfan Liu wrote: > On Wed, Dec 5, 2018 at 5:21 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > On Wed 05-12-18 13:38:17, Pingfan Liu wrote: > > > On Tue, Dec 4, 2018 at 4:56 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > > > > > On Tue 04-12-18 16:20:32, 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. > > > > > > > > I believe we should focus on this. Why does the node have no zonelist > > > > even though all zonelists should be initialized already? Maybe this is > > > > nr_cpus pecularity and we do not initialize all the existing numa nodes. > > > > Or maybe the device is associated to a non-existing node with that > > > > setup. A full dmesg might help us here. > > > > > > > Requiring the machine again, and I got the following without nr_cpus option > > > [root@dell-per7425-03 ~]# cd /sys/devices/system/node/ > > > [root@dell-per7425-03 node]# ls > > > has_cpu has_memory has_normal_memory node0 node1 node2 node3 > > > node4 node5 node6 node7 online possible power uevent > > > [root@dell-per7425-03 node]# cat has_cpu > > > 0-7 > > > [root@dell-per7425-03 node]# cat has_memory > > > 1,5 > > > [root@dell-per7425-03 node]# cat online > > > 0-7 > > > [root@dell-per7425-03 node]# cat possible > > > 0-7 > > > And lscpu shows the following numa-cpu info: > > > NUMA node0 CPU(s): 0,8,16,24 > > > NUMA node1 CPU(s): 2,10,18,26 > > > NUMA node2 CPU(s): 4,12,20,28 > > > NUMA node3 CPU(s): 6,14,22,30 > > > NUMA node4 CPU(s): 1,9,17,25 > > > NUMA node5 CPU(s): 3,11,19,27 > > > NUMA node6 CPU(s): 5,13,21,29 > > > NUMA node7 CPU(s): 7,15,23,31 > > > > > > For the full panic message (I masked some hostname info with xx), > > > please see the attachment. > > > In a short word, it seems a problem with nr_cpus, if without this > > > option, the kernel can bootup correctly. > > > > Yep. > > [ 0.007418] Early memory node ranges > > [ 0.007419] node 1: [mem 0x0000000000001000-0x000000000008efff] > > [ 0.007420] node 1: [mem 0x0000000000090000-0x000000000009ffff] > > [ 0.007422] node 1: [mem 0x0000000000100000-0x000000005c3d6fff] > > [ 0.007422] node 1: [mem 0x00000000643df000-0x0000000068ff7fff] > > [ 0.007423] node 1: [mem 0x000000006c528000-0x000000006fffffff] > > [ 0.007424] node 1: [mem 0x0000000100000000-0x000000047fffffff] > > [ 0.007425] node 5: [mem 0x0000000480000000-0x000000087effffff] > > > > There is clearly no node2. Where did the driver get the node2 from? > Since using nr_cpus=4 , the node2 is not be instanced by x86 initalizing code. > For the normal bootup, having the following: > [ 0.007704] Movable zone start for each node > [ 0.007707] Early memory node ranges > [ 0.007708] node 1: [mem 0x0000000000001000-0x000000000008efff] > [ 0.007709] node 1: [mem 0x0000000000090000-0x000000000009ffff] > [ 0.007711] node 1: [mem 0x0000000000100000-0x000000005c3d6fff] > [ 0.007712] node 1: [mem 0x00000000643df000-0x0000000068ff7fff] > [ 0.007712] node 1: [mem 0x000000006c528000-0x000000006fffffff] > [ 0.007713] node 1: [mem 0x0000000100000000-0x000000047fffffff] > [ 0.007714] node 5: [mem 0x0000000480000000-0x000000087effffff] > [ 0.008434] Zeroed struct page in unavailable ranges: 46490 pages Hmm, this is even more interesting. So even a normal boot doesn't have node 2. So where exactly does the device get its affinity from? I suspect we are looking at two issues here. The first one, and a more important one is that there is a NUMA affinity configured for the device to a non-existing node. The second one is that nr_cpus affects initialization of possible nodes. -- Michal Hocko SUSE Labs
