Re: [PATCH] mm/alloc: fallback to first node if the wanted node offline

[Michal Hocko <mhocko@kernel.org>]

On Fri 07-12-18 17:40:09, Pingfan Liu wrote:
> On Fri, Dec 7, 2018 at 3:53 PM Michal Hocko <mhocko@kernel.org> wrote:
> >
> > On Fri 07-12-18 10:56:51, Pingfan Liu wrote:
> > [...]
> > > In a short word, the fix method should consider about the two factors:
> > > semantic of online-node and the effect on all archs
> >
> > I am pretty sure there is a lot of room for unification in this area.
> > Nevertheless I strongly believe the bug should be fixed firs with the
> > simplest way and all the cleanup should be done on top.
> >
> > Do I get it right that the diff worked for you and I can prepare a full
> > patch?
> >
> Sure, I am glad to test you new patch.

From 46e68be89d9c299fd497b2b8bea3f2add144f17f Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Fri, 7 Dec 2018 12:23:32 +0100
Subject: [PATCH] x86, numa: always initialize all possible nodes

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 moving init_memory_less_node into numa_register_memblks
and always initialize all possible nodes consistently at a single place.

Reported-by: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 arch/x86/mm/numa.c | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 1308f5408bf7..4575ae4d5449 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -527,6 +527,19 @@ static void __init numa_clear_kernel_node_hotplug(void)
 	}
 }
 
+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};
+
+	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.
+	 */
+}
+
 static int __init numa_register_memblks(struct numa_meminfo *mi)
 {
 	unsigned long uninitialized_var(pfn_align);
@@ -592,6 +605,8 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
 			continue;
 
 		alloc_node_data(nid);
+		if (!end)
+			init_memory_less_node(nid);
 	}
 
 	/* Dump memblock with node info and return. */
@@ -721,21 +736,6 @@ 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 +763,6 @@ 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);
 	}
 }
-- 
2.19.2

-- 
Michal Hocko
SUSE Labs