Re: [RFC PATCH] x86, numa: always initialize all possible nodes

Michal Hocko
2019-01-24T14:17:33Z

a friendly ping for this. Does anybody see any problem with this
approach?

On Mon 14-01-19 09:24:16, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> Pingfan Liu has reported the following splat
> [ 5.772742] BUG: unable to handle kernel paging request at 0000000000002088
> [ 5.773618] PGD 0 P4D 0
> [ 5.773618] Oops: 0000 [#1] SMP NOPTI
> [ 5.773618] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.20.0-rc1+ #3
> [ 5.773618] Hardware name: Dell Inc. PowerEdge R7425/02MJ3T, BIOS 1.4.3 06/29/2018
> [ 5.773618] RIP: 0010:__alloc_pages_nodemask+0xe2/0x2a0
> [ 5.773618] Code: 00 00 44 89 ea 80 ca 80 41 83 f8 01 44 0f 44 ea 89 da c1 ea 08 83 e2 01 88 54 24 20 48 8b 54 24 08 48 85 d2 0f 85 46 01 00 00 <3b> 77 08 0f 82 3d 01 00 00 48 89 f8 44 89 ea 48 89
> e1 44 89 e6 89
> [ 5.773618] RSP: 0018:ffffaa600005fb20 EFLAGS: 00010246
> [ 5.773618] RAX: 0000000000000000 RBX: 00000000006012c0 RCX: 0000000000000000
> [ 5.773618] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000002080
> [ 5.773618] RBP: 00000000006012c0 R08: 0000000000000000 R09: 0000000000000002
> [ 5.773618] R10: 00000000006080c0 R11: 0000000000000002 R12: 0000000000000000
> [ 5.773618] R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000002
> [ 5.773618] FS: 0000000000000000(0000) GS:ffff8c69afe00000(0000) knlGS:0000000000000000
> [ 5.773618] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 5.773618] CR2: 0000000000002088 CR3: 000000087e00a000 CR4: 00000000003406e0
> [ 5.773618] Call Trace:
> [ 5.773618] new_slab+0xa9/0x570
> [ 5.773618] ___slab_alloc+0x375/0x540
> [ 5.773618] ? pinctrl_bind_pins+0x2b/0x2a0
> [ 5.773618] __slab_alloc+0x1c/0x38
> [ 5.773618] __kmalloc_node_track_caller+0xc8/0x270
> [ 5.773618] ? pinctrl_bind_pins+0x2b/0x2a0
> [ 5.773618] devm_kmalloc+0x28/0x60
> [ 5.773618] pinctrl_bind_pins+0x2b/0x2a0
> [ 5.773618] really_probe+0x73/0x420
> [ 5.773618] driver_probe_device+0x115/0x130
> [ 5.773618] __driver_attach+0x103/0x110
> [ 5.773618] ? driver_probe_device+0x130/0x130
> [ 5.773618] bus_for_each_dev+0x67/0xc0
> [ 5.773618] ? klist_add_tail+0x3b/0x70
> [ 5.773618] bus_add_driver+0x41/0x260
> [ 5.773618] ? pcie_port_setup+0x4d/0x4d
> [ 5.773618] driver_register+0x5b/0xe0
> [ 5.773618] ? pcie_port_setup+0x4d/0x4d
> [ 5.773618] do_one_initcall+0x4e/0x1d4
> [ 5.773618] ? init_setup+0x25/0x28
> [ 5.773618] kernel_init_freeable+0x1c1/0x26e
> [ 5.773618] ? loglevel+0x5b/0x5b
> [ 5.773618] ? rest_init+0xb0/0xb0
> [ 5.773618] kernel_init+0xa/0x110
> [ 5.773618] ret_from_fork+0x22/0x40
> [ 5.773618] Modules linked in:
> [ 5.773618] CR2: 0000000000002088
> [ 5.773618] ---[ end trace 1030c9120a03d081 ]---
>
> with his AMD machine with the following topology
> 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
>
> [ 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]
>
> and nr_cpus set to 4. The underlying reason is tha the device is bound
> to node 2 which doesn't have any memory and init_cpu_to_node only
> initializes memory-less nodes for possible cpus which nr_cpus restrics.
> This in turn means that proper zonelists are not allocated and the page
> allocator blows up.
>
> Fix the issue by reworking how x86 initializes the memory less nodes.
> The current implementation is hacked into the workflow and it doesn't
> allow any flexibility. There is init_memory_less_node called for each
> offline node that has a CPU as already mentioned above. This will make
> sure that we will have a new online node without any memory. Much later
> on we build a zone list for this node and things seem to work, except
> they do not (e.g. due to nr_cpus). Not to mention that it doesn't really
> make much sense to consider an empty node as online because we just
> consider this node whenever we want to iterate nodes to use and empty
> node is obviously not the best candidate. This is all just too fragile.
>
> Reported-by: Pingfan Liu <kernelfans@gmail.com>
> Tested-by: Pingfan Liu <kernelfans@gmail.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>
> Hi,
> I am sending this as an RFC because I am not sure this is the proper way
> to go myself. I am especially not sure about other architectures
> supporting memoryless nodes (ppc and ia64 AFAICS or are there more?).
>
> I would appreciate a help with those architectures because I couldn't
> really grasp how the memoryless nodes are really initialized there. E.g.
> ppc only seem to call setup_node_data for online nodes but I couldn't
> find any special treatment for nodes without any memory.
>
> Any further help, comments are appreaciated!
>
> arch/x86/mm/numa.c | 27 +++------------------------
> mm/page_alloc.c | 15 +++++++++------
> 2 files changed, 12 insertions(+), 30 deletions(-)
>
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 1308f5408bf7..b3621ee4dfe8 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -216,8 +216,6 @@ static void __init alloc_node_data(int nid)
>
> node_data[nid] = nd;
> memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
> -
> - node_set_online(nid);
> }
>
> /**
> @@ -570,7 +568,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
> return -EINVAL;
>
> /* Finally register nodes. */
> - for_each_node_mask(nid, node_possible_map) {
> + for_each_node_mask(nid, numa_nodes_parsed) {
> u64 start = PFN_PHYS(max_pfn);
> u64 end = 0;
>
> @@ -581,9 +579,6 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
> end = max(mi->blk[i].end, end);
> }
>
> - if (start >= end)
> - continue;
> -
> /*
> * Don't confuse VM with a node that doesn't have the
> * minimum amount of memory:
> @@ -592,6 +587,8 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
> continue;
>
> alloc_node_data(nid);
> + if (end)
> + node_set_online(nid);
> }
>
> /* Dump memblock with node info and return. */
> @@ -721,21 +718,6 @@ void __init x86_numa_init(void)
> numa_init(dummy_numa_init);
> }
>
> -static void __init init_memory_less_node(int nid)
> -{
> - unsigned long zones_size[MAX_NR_ZONES] = {0};
> - unsigned long zholes_size[MAX_NR_ZONES] = {0};
> -
> - /* Allocate and initialize node data. Memory-less node is now online.*/
> - alloc_node_data(nid);
> - free_area_init_node(nid, zones_size, 0, zholes_size);
> -
> - /*
> - * All zonelists will be built later in start_kernel() after per cpu
> - * areas are initialized.
> - */
> -}
> -
> /*
> * Setup early cpu_to_node.
> *
> @@ -763,9 +745,6 @@ void __init init_cpu_to_node(void)
> if (node == NUMA_NO_NODE)
> continue;
>
> - if (!node_online(node))
> - init_memory_less_node(node);
> -
> numa_set_node(cpu, node);
> }
> }
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2ec9cc407216..2e097f336126 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5361,10 +5361,11 @@ static void __build_all_zonelists(void *data)
> if (self && !node_online(self->node_id)) {
> build_zonelists(self);
> } else {
> - for_each_online_node(nid) {
> + for_each_node(nid) {
> pg_data_t *pgdat = NODE_DATA(nid);
>
> - build_zonelists(pgdat);
> + if (pgdat)
> + build_zonelists(pgdat);
> }
>
> #ifdef CONFIG_HAVE_MEMORYLESS_NODES
> @@ -6644,10 +6645,8 @@ static unsigned long __init find_min_pfn_for_node(int nid)
> for_each_mem_pfn_range(i, nid, &start_pfn, NULL, NULL)
> min_pfn = min(min_pfn, start_pfn);
>
> - if (min_pfn == ULONG_MAX) {
> - pr_warn("Could not find start_pfn for node %d\n", nid);
> + if (min_pfn == ULONG_MAX)
> return 0;
> - }
>
> return min_pfn;
> }
> @@ -6991,8 +6990,12 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
> mminit_verify_pageflags_layout();
> setup_nr_node_ids();
> zero_resv_unavail();
> - for_each_online_node(nid) {
> + for_each_node(nid) {
> pg_data_t *pgdat = NODE_DATA(nid);
> +
> + if (!pgdat)
> + continue;
> +
> free_area_init_node(nid, NULL,
> find_min_pfn_for_node(nid), NULL);
>
> --
> 2.20.1
>

--
Michal Hocko
SUSE Labs