Commit e2d59152 authored Jan 08, 2018 by Michael Ellerman

powerpc/pseries: Make RAS IRQ explicitly dependent on DLPAR WQ



The hotplug code uses its own workqueue to handle IRQ requests
(pseries_hp_wq), however that workqueue is initialized after
init_ras_IRQ(). That can lead to a kernel panic if any hotplug
interrupts fire after init_ras_IRQ() but before pseries_hp_wq is
initialised. eg:

  UDP-Lite hash table entries: 2048 (order: 0, 65536 bytes)
  NET: Registered protocol family 1
  Unpacking initramfs...
  (qemu) object_add memory-backend-ram,id=mem1,size=10G
  (qemu) device_add pc-dimm,id=dimm1,memdev=mem1
  Unable to handle kernel paging request for data at address 0xf94d03007c421378
  Faulting instruction address: 0xc00000000012d744
  Oops: Kernel access of bad area, sig: 11 [#1]
  LE SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.15.0-rc2-ziviani+ #26
  task:         (ptrval) task.stack:         (ptrval)
  NIP:  c00000000012d744 LR: c00000000012d744 CTR: 0000000000000000
  REGS:         (ptrval) TRAP: 0380   Not tainted  (4.15.0-rc2-ziviani+)
  MSR:  8000000000009033 <SF,EE,ME,IR,DR,RI,LE>  CR: 28088042  XER: 20040000
  CFAR: c00000000012d3c4 SOFTE: 0
  ...
  NIP [c00000000012d744] __queue_work+0xd4/0x5c0
  LR [c00000000012d744] __queue_work+0xd4/0x5c0
  Call Trace:
  [c0000000fffefb90] [c00000000012d744] __queue_work+0xd4/0x5c0 (unreliable)
  [c0000000fffefc70] [c00000000012dce4] queue_work_on+0xb4/0xf0

This commit makes the RAS IRQ registration explicitly dependent on the
creation of the pseries_hp_wq.

Reported-by: Min Deng <mdeng@redhat.com>
Reported-by: Daniel Henrique Barboza <danielhb@linux.vnet.ibm.com>
Tested-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

parent ecb101ae

arch/powerpc/platforms/pseries/dlpar.c

+18 −3

Original line number	Diff line number	Diff line
		@@ -574,11 +574,26 @@ static ssize_t dlpar_show(struct class class, struct class_attribute attr,

		static CLASS_ATTR_RW(dlpar);

		static int __init pseries_dlpar_init(void)
		int __init dlpar_workqueue_init(void)
		{
		if (pseries_hp_wq)
		return 0;

		pseries_hp_wq = alloc_workqueue("pseries hotplug workqueue",
		WQ_UNBOUND, 1);

		return pseries_hp_wq ? 0 : -ENOMEM;
		}

		static int __init dlpar_sysfs_init(void)
		{
		int rc;

		rc = dlpar_workqueue_init();
		if (rc)
		return rc;

		return sysfs_create_file(kernel_kobj, &class_attr_dlpar.attr);
		}
		machine_device_initcall(pseries, pseries_dlpar_init);
		machine_device_initcall(pseries, dlpar_sysfs_init);

arch/powerpc/platforms/pseries/pseries.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -98,4 +98,6 @@ static inline unsigned long cmo_get_page_size(void)
		return CMO_PageSize;
		}

		int dlpar_workqueue_init(void);

		#endif /* _PSERIES_PSERIES_H */

arch/powerpc/platforms/pseries/ras.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -69,6 +69,7 @@ static int __init init_ras_IRQ(void)
		/* Hotplug Events */
		np = of_find_node_by_path("/event-sources/hot-plug-events");
		if (np != NULL) {
		if (dlpar_workqueue_init() == 0)
		request_event_sources_irqs(np, ras_hotplug_interrupt,
		"RAS_HOTPLUG");
		of_node_put(np);