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Date: Wed, 5 Dec 2018 17:29:31 +0800
From: Pingfan Liu <kernelfans@...il.com>
To: mhocko@...nel.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Vlastimil Babka <vbabka@...e.cz>,
Mike Rapoport <rppt@...ux.vnet.ibm.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node offline
On Wed, Dec 5, 2018 at 5:21 PM Michal Hocko <mhocko@...nel.org> wrote:
>
> On Wed 05-12-18 13:38:17, Pingfan Liu wrote:
> > On Tue, Dec 4, 2018 at 4:56 PM Michal Hocko <mhocko@...nel.org> wrote:
> > >
> > > On Tue 04-12-18 16:20:32, Pingfan Liu wrote:
> > > > On Tue, Dec 4, 2018 at 3:22 PM Michal Hocko <mhocko@...nel.org> 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@...l-per7425-03 ~]# cd /sys/devices/system/node/
> > [root@...l-per7425-03 node]# ls
> > has_cpu has_memory has_normal_memory node0 node1 node2 node3
> > node4 node5 node6 node7 online possible power uevent
> > [root@...l-per7425-03 node]# cat has_cpu
> > 0-7
> > [root@...l-per7425-03 node]# cat has_memory
> > 1,5
> > [root@...l-per7425-03 node]# cat online
> > 0-7
> > [root@...l-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
[ 0.008435] Initmem setup node 1 [mem 0x0000000000001000-0x000000047fffffff]
[ 0.022826] Initmem setup node 5 [mem 0x0000000480000000-0x000000087effffff]
[ 0.024303] ACPI: PM-Timer IO Port: 0x408
[ 0.024320] ACPI: LAPIC_NMI (acpi_id[0xff] high edge lint[0x1])
[ 0.024349] IOAPIC[0]: apic_id 128, version 33, address 0xfec00000, GSI 0-23
[ 0.024354] IOAPIC[1]: apic_id 129, version 33, address 0xfd880000, GSI 24-55
[ 0.024360] IOAPIC[2]: apic_id 130, version 33, address 0xea900000, GSI 56-87
[ 0.024365] IOAPIC[3]: apic_id 131, version 33, address 0xdd900000,
GSI 88-119
[ 0.024371] IOAPIC[4]: apic_id 132, version 33, address 0xd0900000,
GSI 120-151
[ 0.024378] IOAPIC[5]: apic_id 133, version 33, address 0xc3900000,
GSI 152-183
[ 0.024385] IOAPIC[6]: apic_id 134, version 33, address 0xb6900000,
GSI 184-215
[ 0.024391] IOAPIC[7]: apic_id 135, version 33, address 0xa9900000,
GSI 216-247
[ 0.024397] IOAPIC[8]: apic_id 136, version 33, address 0x9c900000,
GSI 248-279
[ 0.024400] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
[ 0.024402] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 low level)
[ 0.024408] Using ACPI (MADT) for SMP configuration information
[ 0.024410] ACPI: HPET id: 0x10228201 base: 0xfed00000
[ 0.024418] smpboot: Allowing 128 CPUs, 96 hotplug CPUs
[ 0.024422] NODE_DATA(0) allocated [mem 0x87efa1000-0x87efcbfff]
[ 0.024424] NODE_DATA(0) on node 5
[ 0.024457] Initmem setup node 0 [mem 0x0000000000000000-0x0000000000000000]
[ 0.024460] NODE_DATA(4) allocated [mem 0x87ef76000-0x87efa0fff]
[ 0.024461] NODE_DATA(4) on node 5
[ 0.024494] Initmem setup node 4 [mem 0x0000000000000000-0x0000000000000000]
[ 0.024497] NODE_DATA(2) allocated [mem 0x87ef4b000-0x87ef75fff]
[ 0.024498] NODE_DATA(2) on node 5
---------------------------------------------------------------------------------->nid=2
[ 0.024530] Initmem setup node 2 [mem 0x0000000000000000-0x0000000000000000]
[ 0.024533] NODE_DATA(6) allocated [mem 0x87ef20000-0x87ef4afff]
[ 0.024534] NODE_DATA(6) on node 5
[ 0.024566] Initmem setup node 6 [mem 0x0000000000000000-0x0000000000000000]
[ 0.024568] NODE_DATA(3) allocated [mem 0x87eef5000-0x87ef1ffff]
Hence, this should be a specific issue with nr_cpus. The attachment is
full message of normal bootup
Thanks,
Pingfan
View attachment "without_nrcpus.txt" of type "text/plain" (69428 bytes)
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