I am getting this crash on a Powerpc system using 3.16.0-rc7 kernel plus some patches related to perf (24x7 counters) that Cody Schafer posted here: https://lkml.org/lkml/2014/5/27/768 I don't get the crash on an unpatched kernel though. I have been staring at the perf event patches, but can't find anything impacting the scheduler. Besides the patches had worked on 3.16.0-rc2 kernel on a different Power system. The crash occurs on an idle system, a minute or two after booting to runlevel 3. kernel/sched/core.c: --- 5877 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd) 5878 { 5879 struct sched_group *sg = sd->groups; 5880 5881 WARN_ON(!sg); 5882 5883 do { 5884 sg->group_weight = cpumask_weight(sched_group_cpus(sg)); --- I tried applying the patch discussed in https://lkml.org/lkml/2014/7/16/386 but doesn't seem to help. diff --git a/kernel/sched/core.c b/kernel/sched/core.c index bc1638b..50702a8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5842,6 +5842,8 @@ build_sched_groups(struct sched_domain *sd, int cpu) continue; group = get_group(i, sdd, &sg); + cpumask_clear(sched_group_cpus(sg)); + sg->sgc->capacity = 0; cpumask_setall(sched_group_mask(sg)); for_each_cpu(j, span) { I am also attaching the debug messages that Peterz added here: https://lkml.org/lkml/2014/7/17/288 Appreciate any debug suggestions. Sukadev ---- Red Hat Enterprise Linux Server 7.0 (Maipo) Kernel 3.16.0-rc7-24x7+ on an ppc64 ltcbrazos2-lp07 login: Red Hat Enterprise Linux Server 7.0 (Maipo) Kernel 3.16.0-rc7-24x7+ on an ppc64 ltcbrazos2-lp07 login: [ 181.915974] ------------[ cut here ]------------ [ 181.915991] WARNING: at ../kernel/sched/core.c:5881 [ 181.915994] Modules linked in: sg cfg80211 rfkill nx_crypto ibmveth pseries_rng xfs libcrc32c sd_mod crc_t10dif crct10dif_common ibmvscsi scsi_transport_srp scsi_tgt dm_mirror dm_region_hash dm_log dm_mod [ 181.916024] CPU: 4 PID: 1087 Comm: kworker/4:2 Not tainted 3.16.0-rc7-24x7+ #15 [ 181.916034] Workqueue: events .topology_work_fn [ 181.916038] task: c0000000dbd40000 ti: c0000000da400000 task.ti: c0000000da400000 [ 181.916043] NIP: c0000000000d7528 LR: c0000000000d7578 CTR: 0000000000000000 [ 181.916047] REGS: c0000000da403580 TRAP: 0700 Not tainted (3.16.0-rc7-24x7+) [ 181.916051] MSR: 8000000100029032 CR: 28484c24 XER: 00000000 [ 181.916063] CFAR: c0000000000d74f4 SOFTE: 1 GPR00: c0000000000d7578 c0000000da403800 c000000000eaa7f0 0000000000000800 GPR04: 0000000000000800 0000000000000800 0000000000000000 c0000000009cf878 GPR08: c0000000009cf880 0000000000000001 0000000000000010 0000000000000000 GPR12: 0000000000000000 c00000000ebe1200 0000000000000800 c0000000cc2f0000 GPR16: c000000000ef0a68 0000000000000078 c0000000e5000000 0000000000000078 GPR20: 0000000000000000 0000000000000001 c0000000cc2f0000 0000000000000001 GPR24: c000000000db4402 000000000000000f 0000000000000000 c0000000dea39300 GPR28: c000000000ef0ae0 c0000000e5440000 0000000000000000 c000000000ef4f7c [ 181.916146] NIP [c0000000000d7528] .build_sched_domains+0xc28/0xd90 [ 181.916151] LR [c0000000000d7578] .build_sched_domains+0xc78/0xd90 [ 181.916155] Call Trace: [ 181.916159] [c0000000da403800] [c0000000000d7578] .build_sched_domains+0xc78/0xd90 (unreliable) [ 181.916166] [c0000000da403950] [c0000000000d7950] .partition_sched_domains+0x260/0x3f0 [ 181.916175] [c0000000da403a30] [c000000000141704] .rebuild_sched_domains_locked+0x54/0x70 [ 181.916182] [c0000000da403ab0] [c000000000143a98] .rebuild_sched_domains+0x28/0x50 [ 181.916188] [c0000000da403b30] [c00000000004f250] .topology_work_fn+0x10/0x30 [ 181.916194] [c0000000da403ba0] [c0000000000b7100] .process_one_work+0x1a0/0x4c0 [ 181.916199] [c0000000da403c40] [c0000000000b7970] .worker_thread+0x180/0x630 [ 181.916205] [c0000000da403d30] [c0000000000bfc88] .kthread+0x108/0x130 [ 181.916214] [c0000000da403e30] [c00000000000a3e4] .ret_from_kernel_thread+0x58/0x74 [ 181.916220] Instruction dump: [ 181.916223] 7f47492a e93c0000 e90a0010 7d0a4378 7d4a482a 814a0000 2f8a0000 419e0008 [ 181.916235] 7f48492a ebdd0010 7fc90074 7929d182 <0b090000> 48000014 60000000 60000000 [ 181.916245] ---[ end trace 6e9d20016598c36c ]--- [ 181.916253] Unable to handle kernel paging request for data at address 0x00000018 [ 181.916257] Faulting instruction address: 0xc00000000039d1c0 [ 181.916263] Oops: Kernel access of bad area, sig: 11 [#1] [ 181.916267] SMP NR_CPUS=2048 NUMA pSeries [ 181.916271] Modules linked in: sg cfg80211 rfkill nx_crypto ibmveth pseries_rng xfs libcrc32c sd_mod crc_t10dif crct10dif_common ibmvscsi scsi_transport_srp scsi_tgt dm_mirror dm_region_hash dm_log dm_mod [ 181.916293] CPU: 4 PID: 1087 Comm: kworker/4:2 Tainted: G W 3.16.0-rc7-24x7+ #15 [ 181.916299] Workqueue: events .topology_work_fn [ 181.916303] task: c0000000dbd40000 ti: c0000000da400000 task.ti: c0000000da400000 [ 181.916309] NIP: c00000000039d1c0 LR: c0000000000d754c CTR: 0000000000000000 [ 181.916313] REGS: c0000000da4034d0 TRAP: 0300 Tainted: G W (3.16.0-rc7-24x7+) [ 181.916317] MSR: 8000000100009032 CR: 28484c24 XER: 00000000 [ 181.916327] CFAR: c000000000009358 DAR: 0000000000000018 DSISR: 40000000 SOFTE: 1 GPR00: c0000000000d754c c0000000da403750 c000000000eaa7f0 0000000000000018 GPR04: 0000000000000800 0000000000000800 0000000000000000 c0000000009cf878 GPR08: c0000000009cf880 0000000000000001 0000000000000010 0000000000000000 GPR12: 0000000000000000 c00000000ebe1200 0000000000000800 c0000000cc2f0000 GPR16: c000000000ef0a68 0000000000000078 c0000000e5000000 0000000000000078 GPR20: 0000000000000000 0000000000000001 c0000000cc2f0000 0000000000000001 GPR24: c000000000db4402 0000000000000020 0000000000000018 0000000000000800 GPR28: 0000000000000020 0000000000000110 0000000000000000 0000000000000010 [ 181.916406] NIP [c00000000039d1c0] .__bitmap_weight+0x70/0x100 [ 181.916411] LR [c0000000000d754c] .build_sched_domains+0xc4c/0xd90 [ 181.916415] Call Trace: [ 181.916418] [c0000000da403750] [c0000000da403800] 0xc0000000da403800 (unreliable) [ 181.916424] [c0000000da403800] [c0000000000d754c] .build_sched_domains+0xc4c/0xd90 [ 181.916430] [c0000000da403950] [c0000000000d7950] .partition_sched_domains+0x260/0x3f0 [ 181.916436] [c0000000da403a30] [c000000000141704] .rebuild_sched_domains_locked+0x54/0x70 [ 181.916442] [c0000000da403ab0] [c000000000143a98] .rebuild_sched_domains+0x28/0x50 [ 181.916448] [c0000000da403b30] [c00000000004f250] .topology_work_fn+0x10/0x30 [ 181.916453] [c0000000da403ba0] [c0000000000b7100] .process_one_work+0x1a0/0x4c0 [ 181.916458] [c0000000da403c40] [c0000000000b7970] .worker_thread+0x180/0x630 [ 181.916463] [c0000000da403d30] [c0000000000bfc88] .kthread+0x108/0x130 [ 181.916468] [c0000000da403e30] [c00000000000a3e4] .ret_from_kernel_thread+0x58/0x74 [ 181.916472] Instruction dump: [ 181.916475] 409d00b4 3bbcffff 3be3fff8 7bbd1f48 3bc00000 7fa3ea14 48000018 60000000 [ 181.916484] 60000000 60000000 60000000 60420000 4bcb74e9 60000000 7fbfe840 [ 181.916493] ---[ end trace 6e9d20016598c36d ]--- [ 181.924408] [ 183.931081] Kernel panic - not syncing: Fatal exception [ 183.954314] Rebooting in 10 seconds..