[PATCHv2 0/3] post the event cpux add/remove besides online/offline during hotplug

[PATCHv2 0/3] post the event cpux add/remove besides online/offline during hotplug

[Pingfan Liu]

v1->v2:
   -1.improve the commit log and explain the reproducing of bug in [3/3]
   -2.re-fragment the series, and [3/3] is the motivation, while [1~2/3] are preparation.   

Pingfan Liu (3):
  powerpc/cpuidle: dynamically register/unregister cpuidle_device during
    hotplug
  powerpc/cpu: dynmamically to create/destroy the file physical_id
    during hotplug
  powerpc/cpu: post the event cpux add/remove instead of online/offline
    during hotplug

 arch/powerpc/include/asm/smp.h               |  1 +
 arch/powerpc/kernel/sysfs.c                  | 26 ++++++++++++++------------
 arch/powerpc/platforms/pseries/hotplug-cpu.c |  3 +++
 drivers/cpuidle/cpuidle-powernv.c            |  2 ++
 drivers/cpuidle/cpuidle-pseries.c            |  2 ++
 5 files changed, 22 insertions(+), 12 deletions(-)

-- 
2.7.4

[PATCHv2 1/3] powerpc/cpuidle: dynamically register/unregister cpuidle_device during hotplug

[Pingfan Liu]

cpuidle_device is touched during the cpu hotplug. In order to cope with the incoming
patch [3/3], which causes the dir /sys/../cpuX is created/destroyed during hotplug,
we also need to create the file cpuX/cpuidle dynamically.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Reviewed-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
---
 drivers/cpuidle/cpuidle-powernv.c | 2 ++
 drivers/cpuidle/cpuidle-pseries.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 1a8234e..962c944 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -144,6 +144,7 @@ static int powernv_cpuidle_cpu_online(unsigned int cpu)
 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 
 	if (dev && cpuidle_get_driver()) {
+		cpuidle_register_device(dev);
 		cpuidle_pause_and_lock();
 		cpuidle_enable_device(dev);
 		cpuidle_resume_and_unlock();
@@ -159,6 +160,7 @@ static int powernv_cpuidle_cpu_dead(unsigned int cpu)
 		cpuidle_pause_and_lock();
 		cpuidle_disable_device(dev);
 		cpuidle_resume_and_unlock();
+		cpuidle_unregister_device(dev);
 	}
 	return 0;
 }
diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c
index 9e56bc4..a53be8a 100644
--- a/drivers/cpuidle/cpuidle-pseries.c
+++ b/drivers/cpuidle/cpuidle-pseries.c
@@ -193,6 +193,7 @@ static int pseries_cpuidle_cpu_online(unsigned int cpu)
 	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 
 	if (dev && cpuidle_get_driver()) {
+		cpuidle_register_device(dev);
 		cpuidle_pause_and_lock();
 		cpuidle_enable_device(dev);
 		cpuidle_resume_and_unlock();
@@ -208,6 +209,7 @@ static int pseries_cpuidle_cpu_dead(unsigned int cpu)
 		cpuidle_pause_and_lock();
 		cpuidle_disable_device(dev);
 		cpuidle_resume_and_unlock();
+		cpuidle_unregister_device(dev);
 	}
 	return 0;
 }
-- 
2.7.4

[PATCHv2 2/3] powerpc/cpu: dynmamically to create/destroy the file physical_id during hotplug

[Pingfan Liu]

In order to cope with the incoming patch [3/3], which causes the dir
/sys/../cpuX is created/destroyed during hotplug, we also need to create
the file cpuX/physical_id dynamically.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Reported-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/sysfs.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 04d0bbd..a05ab5e 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -716,6 +716,16 @@ static struct device_attribute pa6t_attrs[] = {
 #endif /* HAS_PPC_PMC_PA6T */
 #endif /* HAS_PPC_PMC_CLASSIC */
 
+/* Only valid if CPU is present. */
+static ssize_t show_physical_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+
+	return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->dev.id));
+}
+static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);
+
 static int register_cpu_online(unsigned int cpu)
 {
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -723,6 +733,8 @@ static int register_cpu_online(unsigned int cpu)
 	struct device_attribute *attrs, *pmc_attrs;
 	int i, nattrs;
 
+	device_create_file(&c->dev, &dev_attr_physical_id);
+
 	/* For cpus present at boot a reference was already grabbed in register_cpu() */
 	if (!s->of_node)
 		s->of_node = of_get_cpu_node(cpu, NULL);
@@ -816,6 +828,7 @@ static int unregister_cpu_online(unsigned int cpu)
 
 	BUG_ON(!c->hotpluggable);
 
+	device_remove_file(s, &dev_attr_physical_id);
 #ifdef CONFIG_PPC64
 	if (cpu_has_feature(CPU_FTR_SMT))
 		device_remove_file(s, &dev_attr_smt_snooze_delay);
@@ -1017,16 +1030,6 @@ static void register_nodes(void)
 
 #endif
 
-/* Only valid if CPU is present. */
-static ssize_t show_physical_id(struct device *dev,
-				struct device_attribute *attr, char *buf)
-{
-	struct cpu *cpu = container_of(dev, struct cpu, dev);
-
-	return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->dev.id));
-}
-static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);
-
 static int __init topology_init(void)
 {
 	int cpu, r;
@@ -1049,7 +1052,6 @@ static int __init topology_init(void)
 		if (cpu_online(cpu) || c->hotpluggable) {
 			register_cpu(c, cpu);
 
-			device_create_file(&c->dev, &dev_attr_physical_id);
 		}
 	}
 	r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/topology:online",
-- 
2.7.4

[PATCHv2 3/3] powerpc/cpu: post the event cpux add/remove instead of online/offline during hotplug

[Pingfan Liu]

Technically speaking, echo 1/0 > cpuX/online is only a subset of cpu
hotplug/unplug, i.e. add/remove. The latter one includes the physical
adding/removing of a cpu device. Some user space tools such as kexec-tools
resort to the event add/remove to automatically rebuild dtb.
If the dtb is not rebuilt correctly, we may hang on 2nd kernel due to
lack the info of boot-cpu-hwid in dtb.

The steps to trigger the bug: (suppose 8 threads/core)
    drmgr -c cpu -r -q 1
    systemctl restart kdump.service
    drmgr -c cpu -a -q 1
    taskset -c 11 sh -c "echo c > /proc/sysrq-trigger"

Then, failure info:
    [  205.299528] SysRq : Trigger a crash
    [  205.299551] Unable to handle kernel paging request for data at address 0x00000000
    [  205.299558] Faulting instruction address: 0xc0000000006001a0
    [  205.299564] Oops: Kernel access of bad area, sig: 11 [#1]
    [  205.299569] SMP NR_CPUS=2048 NUMA pSeries
    [  205.299575] Modules linked in: macsec sctp_diag sctp tcp_diag udp_diag inet_diag unix_diag af_packet_diag netlink_diag ip6t_rpfilter ipt_REJECT nf_reject_ipv4 ip6t_REJECT nf_reject_ipv6
    xt_conntrack ip_set nfnetlink ebtable_nat ebtable_broute bridge stp llc ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw iptable_nat
    nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter xfs libcrc32c sg
    pseries_rng binfmt_misc ip_tables ext4 mbcache jbd2 sd_mod crc_t10dif crct10dif_generic crct10dif_common ibmvscsi scsi_transport_srp ibmveth scsi_tgt dm_mirror dm_region_hash dm_log dm_mod
    [  205.299658] CPU: 11 PID: 2521 Comm: bash Not tainted 3.10.0-799.el7.ppc64le #1
    [  205.299664] task: c00000017bcd15e0 ti: c00000014f410000 task.ti: c00000014f410000
    [  205.299670] NIP: c0000000006001a0 LR: c000000000600ddc CTR: c000000000600180
    [  205.299676] REGS: c00000014f413a70 TRAP: 0300   Not tainted  (3.10.0-799.el7.ppc64le)
    [  205.299681] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 28222822  XER: 00000001
    [  205.299696] CFAR: c000000000009368 DAR: 0000000000000000 DSISR: 42000000 SOFTE: 1
    GPR00: c000000000600dbc c00000014f413cf0 c000000001263200 0000000000000063
    GPR04: c0000000019ca818 c0000000019db5f8 00000000000000c2 c00000000140aa30
    GPR08: 0000000000000007 0000000000000001 0000000000000000 c00000000140fc60
    GPR12: c000000000600180 c000000007b36300 0000000010139e58 0000000040000000
    GPR16: 000000001013b5d0 0000000000000000 00000000101306fc 0000000010139de4
    GPR20: 0000000010139de8 0000000010093150 0000000000000000 0000000000000000
    GPR24: 000000001013b5e0 00000000100fa0e8 0000000000000007 c0000000011af1c8
    GPR28: 0000000000000063 c0000000011af588 c000000001179ba8 0000000000000002
    [  205.299770] NIP [c0000000006001a0] sysrq_handle_crash+0x20/0x30
    [  205.299776] LR [c000000000600ddc] write_sysrq_trigger+0x10c/0x230
    [  205.299781] Call Trace:
    [  205.299786] [c00000014f413cf0] [c000000000600dbc] write_sysrq_trigger+0xec/0x230 (unreliable)
    [  205.299794] [c00000014f413d90] [c0000000003eb2c4] proc_reg_write+0x84/0x120
    [  205.299801] [c00000014f413dd0] [c000000000330a80] SyS_write+0x150/0x400
    [  205.299808] [c00000014f413e30] [c00000000000a184] system_call+0x38/0xb4
    [  205.299813] Instruction dump:
    [  205.299816] 409effb8 7fc3f378 4bfff381 4bffffac 3c4c00c6 38423080 3d42fff1 394a6930
    [  205.299827] 39200001 912a0000 7c0004ac 39400000 <992a0000> 4e800020 60000000 60420000
    [  205.299838] ---[ end trace f590a5dbd3f63aab ]---
    [  205.301812]
    [  205.301829] Sending IPI to other CPUs
    [  205.302846] IPI complete
    I'm in purgatory
          -- > hang up here

This patch uses the interface register_/unregister_cpu to fix the problem

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Reported-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/smp.h               | 1 +
 arch/powerpc/kernel/sysfs.c                  | 2 +-
 arch/powerpc/platforms/pseries/hotplug-cpu.c | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index fac963e..3ef730d 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -35,6 +35,7 @@ extern int spinning_secondaries;
 extern void cpu_die(void);
 extern int cpu_to_chip_id(int cpu);
 
+DECLARE_PER_CPU(struct cpu, cpu_devices);
 #ifdef CONFIG_SMP
 
 struct smp_ops_t {
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index a05ab5e..dbbcc96 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -26,7 +26,7 @@
 #include <asm/lppaca.h>
 #endif
 
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
+DEFINE_PER_CPU(struct cpu, cpu_devices);
 
 /*
  * SMT snooze delay stuff, 64-bit only for now
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 652d3e96..27a1551 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -367,6 +367,7 @@ static int dlpar_online_cpu(struct device_node *dn)
 			cpu_maps_update_done();
 			timed_topology_update(1);
 			find_and_online_cpu_nid(cpu);
+			register_cpu(&per_cpu(cpu_devices, cpu), cpu);
 			rc = device_online(get_cpu_device(cpu));
 			if (rc)
 				goto out;
@@ -541,6 +542,8 @@ static int dlpar_offline_cpu(struct device_node *dn)
 				rc = device_offline(get_cpu_device(cpu));
 				if (rc)
 					goto out;
+				unregister_cpu(container_of(get_cpu_device(cpu),
+							struct cpu, dev));
 				cpu_maps_update_begin();
 				break;
 
-- 
2.7.4

Re: [PATCHv2 0/3] post the event cpux add/remove besides online/offline during hotplug

[Pingfan Liu]

Maintainers, ping? Any suggestion? I encounter such issue on redhat
RHEL and FEDORA

On Mon, Apr 16, 2018 at 2:35 PM, Pingfan Liu <kernelfans@gmail.com> wrote:
> v1->v2:
>    -1.improve the commit log and explain the reproducing of bug in [3/3]
>    -2.re-fragment the series, and [3/3] is the motivation, while [1~2/3] are preparation.
>
> Pingfan Liu (3):
>   powerpc/cpuidle: dynamically register/unregister cpuidle_device during
>     hotplug
>   powerpc/cpu: dynmamically to create/destroy the file physical_id
>     during hotplug
>   powerpc/cpu: post the event cpux add/remove instead of online/offline
>     during hotplug
>
>  arch/powerpc/include/asm/smp.h               |  1 +
>  arch/powerpc/kernel/sysfs.c                  | 26 ++++++++++++++------------
>  arch/powerpc/platforms/pseries/hotplug-cpu.c |  3 +++
>  drivers/cpuidle/cpuidle-powernv.c            |  2 ++
>  drivers/cpuidle/cpuidle-pseries.c            |  2 ++
>  5 files changed, 22 insertions(+), 12 deletions(-)
>
> --
> 2.7.4
>