On Thu, Jan 24, 2019 at 03:17:27PM +0100, Michal Hocko wrote:
> a friendly ping for this. Does anybody see any problem with this
> approach?
FWIW, it looks fine to me.
It'd just be nice to have a few more words in the changelog about *how* the
x86 init was reworked ;-)
> On Mon 14-01-19 09:24:16, Michal Hocko wrote:
> > From: Michal Hocko <mho...@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 <kernelf...@gmail.com>
> > Tested-by: Pingfan Liu <kernelf...@gmail.com>
> > Signed-off-by: Michal Hocko <mho...@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
>
--
Sincerely yours,
Mike.
