* Jan Stancek <jstan...@redhat.com> [2016-01-09 18:03:55]:
> Hi,
>
> I'm seeing bare metal ppc64le system crashing early during boot
> with latest upstream kernel (4.4.0-rc8):
>
> # git describe
> v4.4-rc8-96-g751e5f5
>
> [ 0.625451] Unable to handle kernel paging request for data at address
> 0x00000000
> [ 0.625586] Faulting instruction address: 0xc0000000004ae000
> [ 0.625698] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 0.625789] SMP NR_CPUS=2048 NUMA PowerNV
> [ 0.625879] Modules linked in:
> [ 0.625973] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc8+ #6
> [ 0.626087] task: c000002ff4300000 ti: c000002ff6084000 task.ti:
> c000002ff6084000
> [ 0.626224] NIP: c0000000004ae000 LR: c00000000090b9e4 CTR:
> 0000000000000003
> [ 0.626361] REGS: c000002ff6087930 TRAP: 0300 Not tainted (4.4.0-rc8+)
> [ 0.626475] MSR: 9000000100009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 48002044
> XER: 20000000
> [ 0.626808] CFAR: c000000000008468 DAR: 0000000000000000 DSISR: 40000000
> SOFTE: 1
> GPR00: c00000000090b9ac c000002ff6087bb0 c000000001700900 c000003ff229e080
> GPR04: c000003ff229e080 0000000000000000 0000000000000003 0000000000000001
> GPR08: 0000000000000000 0000000000000000 0000000000000010 9000000100001003
> GPR12: 0000000000002200 c00000000fb40000 c00000000000bd68 0000000000000002
> GPR16: 0000000000000028 c000000000b25940 c00000000173ffa4 0000000000000000
> GPR20: c000000000b259d8 c000000000b259e0 c000000000b259e8 0000000000000000
> GPR24: c000003ff229e080 0000000000000000 c00000000189b180 0000000000000000
> GPR28: 0000000000000000 c000000001740a94 0000000000000002 0000000000000002
> [ 0.627925] NIP [c0000000004ae000] __bitmap_or+0x30/0x50
> [ 0.627973] LR [c00000000090b9e4] sched_init_numa+0x440/0x7c8
> [ 0.628030] Call Trace:
> [ 0.628054] [c000002ff6087bb0] [c00000000090b9ac]
> sched_init_numa+0x408/0x7c8 (unreliable)
> [ 0.628136] [c000002ff6087ca0] [c000000000c60718] sched_init_smp+0x60/0x238
> [ 0.628206] [c000002ff6087d00] [c000000000c44294]
> kernel_init_freeable+0x1fc/0x3b4
> [ 0.628286] [c000002ff6087dc0] [c00000000000bd84] kernel_init+0x24/0x140
> [ 0.628356] [c000002ff6087e30] [c000000000009544]
> ret_from_kernel_thread+0x5c/0x98
> [ 0.628435] Instruction dump:
> [ 0.628470] 38c6003f 78c9d183 4d820020 38c9ffff 39200000 78c60020 38c60001
> 7cc903a6
> [ 0.628587] 60000000 60000000 60000000 60420000 <7d05482a> 7d44482a
> 7d0a5378 7d43492a
> [ 0.628711] ---[ end trace b423f3e02b333fbf ]---
> [ 0.628757]
> [ 2.628822] Kernel panic - not syncing: Fatal exception
> [ 2.628969] Rebooting in 10 seconds..[ 0.000000] OPAL V3 detected !
>
....
> The crash goes away if I revert following commit:
> commit c118baf802562688d46e6002f2b5fe66b947da21
> Author: Raghavendra K T <raghavendra...@linux.vnet.ibm.com>
> Date: Thu Nov 5 18:46:29 2015 -0800
> arch/powerpc/mm/numa.c: do not allocate bootmem memory for non existing
> nodes
>
Something like below should fix. I 'll send it in a separate email
marking Peter and Ingo. Basically for_each_node conversion
has targeted only slowpaths / used_once sort of functions.
But it seems there was a cpumask_or in sched_init_numa that used
unallocated node.
Sorry for getting back late.. Was overcautious checking x86/power
w/ and w/o DEBUG_PER_CPU_MAPS
---8<-----
From 6680994a5a8dde7eccfbd2bffde341fdff2aed63 Mon Sep 17 00:00:00 2001
From: Raghavendra K T <raghavendra...@linux.vnet.ibm.com>
Date: Fri, 15 Jan 2016 18:19:56 +0530
Subject: [PATCH] Fix: PowerNV crash with 4.4.0-rc8 at sched_init_numa
Commit c118baf80256 ("arch/powerpc/mm/numa.c: do not allocate bootmem
memory for non existing nodes") avoided bootmem memory allocation for
non existent nodes.
When DEBUG_PER_CPU_MAPS enabled, powerNV system failed to boot because
in sched_init_numa, cpumask_or operation was done on unallocated nodes.
Fix that by making cpumask_or operation only on existing nodes.
[ Tested with and w/o DEBUG_PER_CPU_MAPS on x86 and powerpc ]
Reported-by: Jan Stancek <jstan...@redhat.com>
Signed-off-by: Raghavendra K T <raghavendra...@linux.vnet.ibm.com>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 44253ad..474658b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6840,7 +6840,7 @@ static void sched_init_numa(void)
sched_domains_numa_masks[i][j] = mask;
- for (k = 0; k < nr_node_ids; k++) {
+ for_each_node(k) {
if (node_distance(j, k) >
sched_domains_numa_distance[i])
continue;
--
1.7.11.7
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