[PATCH] powerpc/pseries: safely roll back failed DLPAR cpu add
Nathan Lynch
nathanl at linux.ibm.com
Fri Sep 20 08:34:00 AEST 2019
dlpar_online_cpu() attempts to online all threads of a core that has
been added to an LPAR. If onlining a non-primary thread
fails (e.g. due to an allocation failure), the core is left with at
least one thread online. dlpar_cpu_add() attempts to roll back the
whole operation, releasing the core back to the platform. However,
since some threads of the core being removed are still online, the
BUG_ON(cpu_online(cpu)) in pseries_remove_processor() strikes:
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 3 PID: 8587 Comm: drmgr Not tainted 5.3.0-rc2-00190-g9b123d1ea237-dirty #46
NIP: c0000000000eeb2c LR: c0000000000eeac4 CTR: c0000000000ee9e0
REGS: c0000001f745b6c0 TRAP: 0700 Not tainted (5.3.0-rc2-00190-g9b123d1ea237-dirty)
MSR: 800000010282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 44002448 XER: 00000000
CFAR: c00000000195d718 IRQMASK: 0
GPR00: c0000000000eeac4 c0000001f745b950 c0000000032f6200 0000000000000008
GPR04: 0000000000000008 c000000003349c78 0000000000000040 00000000000001ff
GPR08: 0000000000000008 0000000000000000 0000000000000001 0007ffffffffffff
GPR12: 0000000084002844 c00000001ecacb80 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000008
GPR24: c000000003349ee0 c00000000334a2e4 c0000000fca4d7a8 c000000001d20048
GPR28: 0000000000000001 ffffffffffffffff ffffffffffffffff c0000000fca4d7c4
NIP [c0000000000eeb2c] pseries_smp_notifier+0x14c/0x2e0
LR [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0
Call Trace:
[c0000001f745b950] [c0000000000eeac4] pseries_smp_notifier+0xe4/0x2e0 (unreliable)
[c0000001f745ba10] [c0000000001ac774] notifier_call_chain+0xb4/0x190
[c0000001f745bab0] [c0000000001ad62c] blocking_notifier_call_chain+0x7c/0xb0
[c0000001f745baf0] [c00000000167bda0] of_detach_node+0xc0/0x110
[c0000001f745bb50] [c0000000000e7ae4] dlpar_detach_node+0x64/0xa0
[c0000001f745bb80] [c0000000000edefc] dlpar_cpu_add+0x31c/0x360
[c0000001f745bc10] [c0000000000ee980] dlpar_cpu_probe+0x50/0xb0
[c0000001f745bc50] [c00000000002cf70] arch_cpu_probe+0x40/0x70
[c0000001f745bc70] [c000000000ccd808] cpu_probe_store+0x48/0x80
[c0000001f745bcb0] [c000000000cbcef8] dev_attr_store+0x38/0x60
[c0000001f745bcd0] [c00000000059c980] sysfs_kf_write+0x70/0xb0
[c0000001f745bd10] [c00000000059afb8] kernfs_fop_write+0xf8/0x280
[c0000001f745bd60] [c0000000004b437c] __vfs_write+0x3c/0x70
[c0000001f745bd80] [c0000000004b8710] vfs_write+0xd0/0x220
[c0000001f745bdd0] [c0000000004b8acc] ksys_write+0x7c/0x140
[c0000001f745be20] [c00000000000bbd8] system_call+0x5c/0x68
Move dlpar_offline_cpu() before dlpar_online_cpu() so the latter can
use the former to re-offline any threads it has onlined when it
encounters an error.
Signed-off-by: Nathan Lynch <nathanl at linux.ibm.com>
---
arch/powerpc/platforms/pseries/hotplug-cpu.c | 118 ++++++++++---------
1 file changed, 60 insertions(+), 58 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index bbda646b63b5..50e1a9b9b1d5 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -338,6 +338,63 @@ static void pseries_remove_processor(struct device_node *np)
cpu_maps_update_done();
}
+static int dlpar_offline_cpu(struct device_node *dn)
+{
+ int rc = 0;
+ unsigned int cpu;
+ int len, nthreads, i;
+ const __be32 *intserv;
+ u32 thread;
+
+ intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
+ if (!intserv)
+ return -EINVAL;
+
+ nthreads = len / sizeof(u32);
+
+ cpu_maps_update_begin();
+ for (i = 0; i < nthreads; i++) {
+ thread = be32_to_cpu(intserv[i]);
+ for_each_present_cpu(cpu) {
+ if (get_hard_smp_processor_id(cpu) != thread)
+ continue;
+
+ if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
+ break;
+
+ if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
+ set_preferred_offline_state(cpu,
+ CPU_STATE_OFFLINE);
+ cpu_maps_update_done();
+ timed_topology_update(1);
+ rc = device_offline(get_cpu_device(cpu));
+ if (rc)
+ goto out;
+ cpu_maps_update_begin();
+ break;
+
+ }
+
+ /*
+ * The cpu is in CPU_STATE_INACTIVE.
+ * Upgrade it's state to CPU_STATE_OFFLINE.
+ */
+ set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
+ BUG_ON(plpar_hcall_norets(H_PROD, thread)
+ != H_SUCCESS);
+ __cpu_die(cpu);
+ break;
+ }
+ if (cpu == num_possible_cpus())
+ printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
+ }
+ cpu_maps_update_done();
+
+out:
+ return rc;
+
+}
+
static int dlpar_online_cpu(struct device_node *dn)
{
int rc = 0;
@@ -364,8 +421,10 @@ static int dlpar_online_cpu(struct device_node *dn)
timed_topology_update(1);
find_and_online_cpu_nid(cpu);
rc = device_online(get_cpu_device(cpu));
- if (rc)
+ if (rc) {
+ dlpar_offline_cpu(dn);
goto out;
+ }
cpu_maps_update_begin();
break;
@@ -505,63 +564,6 @@ static ssize_t dlpar_cpu_add(u32 drc_index)
return rc;
}
-static int dlpar_offline_cpu(struct device_node *dn)
-{
- int rc = 0;
- unsigned int cpu;
- int len, nthreads, i;
- const __be32 *intserv;
- u32 thread;
-
- intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
- if (!intserv)
- return -EINVAL;
-
- nthreads = len / sizeof(u32);
-
- cpu_maps_update_begin();
- for (i = 0; i < nthreads; i++) {
- thread = be32_to_cpu(intserv[i]);
- for_each_present_cpu(cpu) {
- if (get_hard_smp_processor_id(cpu) != thread)
- continue;
-
- if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
- break;
-
- if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
- set_preferred_offline_state(cpu,
- CPU_STATE_OFFLINE);
- cpu_maps_update_done();
- timed_topology_update(1);
- rc = device_offline(get_cpu_device(cpu));
- if (rc)
- goto out;
- cpu_maps_update_begin();
- break;
-
- }
-
- /*
- * The cpu is in CPU_STATE_INACTIVE.
- * Upgrade it's state to CPU_STATE_OFFLINE.
- */
- set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
- BUG_ON(plpar_hcall_norets(H_PROD, thread)
- != H_SUCCESS);
- __cpu_die(cpu);
- break;
- }
- if (cpu == num_possible_cpus())
- printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
- }
- cpu_maps_update_done();
-
-out:
- return rc;
-
-}
-
static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
{
int rc;
--
2.20.1
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