linux.git/arch/powerpc/platforms/pseries/hotplug-memory.c, branch v3.16.35

powerpc/pseries: Failure on removing device node

2014-09-17T16:21:56+00:00

commit f1b3929c232784580e5d8ee324b6bc634e709575 upstream.

While running command "drmgr -c phb -r -s 'PHB 528'", following
backtrace jumped out because the target device node isn't marked
with OF_DETACHED by of_detach_node(), which caused by error
returned from memory hotplug related reconfig notifier when
disabling CONFIG_MEMORY_HOTREMOVE. The patch fixes it.

ERROR: Bad of_node_put() on /pci@800000020000210/ethernet@0
CPU: 14 PID: 2252 Comm: drmgr Tainted: G        W     3.16.0+ #427
Call Trace:
[c000000012a776a0] [c000000000013d9c] .show_stack+0x88/0x148 (unreliable)
[c000000012a77750] [c00000000083cd34] .dump_stack+0x7c/0x9c
[c000000012a777d0] [c0000000006807c4] .of_node_release+0x58/0xe0
[c000000012a77860] [c00000000038a7d0] .kobject_release+0x174/0x1b8
[c000000012a77900] [c00000000038a884] .kobject_put+0x70/0x78
[c000000012a77980] [c000000000681680] .of_node_put+0x28/0x34
[c000000012a77a00] [c000000000681ea8] .__of_get_next_child+0x64/0x70
[c000000012a77a90] [c000000000682138] .of_find_node_by_path+0x1b8/0x20c
[c000000012a77b40] [c000000000051840] .ofdt_write+0x308/0x688
[c000000012a77c20] [c000000000238430] .proc_reg_write+0xb8/0xd4
[c000000012a77cd0] [c0000000001cbeac] .vfs_write+0xec/0x1f8
[c000000012a77d70] [c0000000001cc3b0] .SyS_write+0x58/0xa0
[c000000012a77e30] [c00000000000a064] syscall_exit+0x0/0x98

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Allow ppc_md platform hook to override memory_block_size_bytes

2014-06-05T03:20:39+00:00

The pseries platform code unconditionally overrides
memory_block_size_bytes regardless of the running platform.

Create a ppc_md hook that so each platform can choose to
do what it wants.

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Protect remove_memory() with device hotplug lock

2014-04-28T06:32:14+00:00

While testing memory hot-remove, I found following dead lock:

Process #1141 is drmgr, trying to remove some memory, i.e. memory499.
It holds the memory_hotplug_mutex, and blocks when trying to remove file
"online" under dir memory499, in kernfs_drain(), at
        wait_event(root->deactivate_waitq,
                   atomic_read(&kn->active) == KN_DEACTIVATED_BIAS);

Process #1120 is trying to online memory499 by
   echo 1 > memory499/online

In .kernfs_fop_write, it uses kernfs_get_active() to increase
&kn->active, thus blocking process #1141. While itself is blocked later
when trying to acquire memory_hotplug_mutex, which is held by process

The backtrace of both processes are shown below:

[] 0xc000000001b18600
[] .__switch_to+0x144/0x200
[] .online_pages+0x74/0x7b0
[] .memory_subsys_online+0x9c/0x150
[] .device_online+0xb8/0x120
[] .online_store+0xb4/0xc0
[] .dev_attr_store+0x64/0xa0
[] .sysfs_kf_write+0x7c/0xb0
[] .kernfs_fop_write+0x154/0x1e0
[] .vfs_write+0xe0/0x260
[] .SyS_write+0x64/0x110
[] syscall_exit+0x0/0x7c

[] 0xc000000001b18600
[] .__switch_to+0x144/0x200
[] .__kernfs_remove+0x204/0x300
[] .kernfs_remove_by_name_ns+0x68/0xf0
[] .sysfs_remove_file_ns+0x38/0x60
[] .device_remove_attrs+0x54/0xc0
[] .device_del+0x158/0x250
[] .device_unregister+0x34/0xa0
[] .unregister_memory_section+0x164/0x170
[] .__remove_pages+0x108/0x4c0
[] .arch_remove_memory+0x60/0xc0
[] .remove_memory+0x8c/0xe0
[] .pseries_remove_memblock+0xd4/0x160
[] .pseries_memory_notifier+0x27c/0x290
[] .notifier_call_chain+0x8c/0x100
[] .__blocking_notifier_call_chain+0x6c/0xe0
[] .of_property_notify+0x7c/0xc0
[] .of_update_property+0x3c/0x1b0
[] .ofdt_write+0x3dc/0x740
[] .proc_reg_write+0xac/0x110
[] .vfs_write+0xe0/0x260
[] .SyS_write+0x64/0x110
[] syscall_exit+0x0/0x7c

This patch uses lock_device_hotplug() to protect remove_memory() called
in pseries_remove_memblock(), which is also stated before function
remove_memory():

 * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
 * and online/offline operations before this call, as required by
 * try_offline_node().
 */
void __ref remove_memory(int nid, u64 start, u64 size)

With this lock held, the other process(#1120 above) trying to online the
memory block will retry the system call when calling
lock_device_hotplug_sysfs(), and finally find No such device error.

Signed-off-by: Li Zhong 
Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Use remove_memory() to remove memory

2014-03-07T04:53:13+00:00

The memory remove code for powerpc/pseries should call remove_memory()
so that we are holding the hotplug_memory lock during memory remove
operations.

This patch updates the memory node remove handler to call remove_memory()
and adds a ppc_md.remove_memory() entry to handle pseries specific work
that is called from arch_remove_memory().

During memory remove in pseries_remove_memblock() we have to stay with
removing memory one section at a time. This is needed because of how memory
resources are handled. During memory add for pseries (via the probe file in
sysfs) we add memory one section at a time which gives us a memory resource
for each section. Future patches will aim to address this so will not have
to remove memory one section at a time.

Signed-off-by: Nathan Fontenot 
Signed-off-by: Benjamin Herrenschmidt

powerpc: add explicit OF includes

2013-10-10T01:04:11+00:00

When removing prom.h include by of.h, several OF headers will no longer
be implicitly included. Add explicit includes of of_*.h as needed.

Signed-off-by: Rob Herring 
Acked-by: Grant Likely 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Anatolij Gustschin 
Cc: Kumar Gala 
Cc: Olof Johansson 
Cc: linuxppc-dev@lists.ozlabs.org

mm, hotplug: avoid compiling memory hotremove functions when disabled

2013-04-29T22:54:37+00:00

__remove_pages() is only necessary for CONFIG_MEMORY_HOTREMOVE.  PowerPC
pseries will return -EOPNOTSUPP if unsupported.

Adding an #ifdef causes several other functions it depends on to also
become unnecessary, which saves in .text when disabled (it's disabled in
most defconfigs besides powerpc, including x86).  remove_memory_block()
becomes static since it is not referenced outside of
drivers/base/memory.c.

Build tested on x86 and powerpc with CONFIG_MEMORY_HOTREMOVE both enabled
and disabled.

Signed-off-by: David Rientjes 
Acked-by: Toshi Kani 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Greg Kroah-Hartman 
Cc: Wen Congyang 
Cc: Tang Chen 
Cc: Yasuaki Ishimatsu 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc+of: Add of node/property notification chain for adds and removes

2012-11-15T01:56:41+00:00

This patch moves the notification chain for updates to the device tree
from the powerpc/pseries code to the base OF code. This makes this
functionality available to all architectures.

Additionally the notification chain is updated to allow notifications
for property add/remove/update. To make this work a pointer to a new
struct (of_prop_reconfig) is passed to the routines in the notification chain.
The of_prop_reconfig property contains a pointer to the node containing the
property and a pointer to the property itself. In the case of property
updates, the property pointer refers to the new property.

Signed-off-by: Nathan Fontenot 
Acked-by: Rob Herring 
Acked-by: Grant Likely 
Signed-off-by: Benjamin Herrenschmidt

arch/powerpc/platforms/pseries/hotplug-memory.c: section removal cleanups

2012-10-10T23:50:14+00:00

Followups to d760afd4d257 ("memory-hotplug: suppress "Trying to free
nonexistent resource " warning").

 - use unsigned long type, as overflows are conceivable

 - rename `i' to the less-misleading and more informative `section'

Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arch/powerpc/platforms/pseries/hotplug-memory.c: fix section handling code

2012-10-10T23:50:13+00:00

Fix

  arch/powerpc/platforms/pseries/hotplug-memory.c: In function 'pseries_remove_memblock':
  arch/powerpc/platforms/pseries/hotplug-memory.c:103:17: error: unused variable 'pfn' [-Werror=unused-variable]

Caused by commit d760afd4d257 ("memory-hotplug: suppress "Trying to free
nonexistent resource " warning").

Reported-by: Stephen Rothwell 
Cc: Yasuaki Ishimatsu 
Tested-by: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Tested-by: Nathan Fontenot 
Tested-by: Benjamin Herrenschmidt 
Signed-off-by: Linus Torvalds

memory-hotplug: suppress "Trying to free nonexistent resource " warning

2012-10-09T07:23:04+00:00

When our x86 box calls __remove_pages(), release_mem_region() shows many
warnings.  And x86 box cannot unregister iomem_resource.

  "Trying to free nonexistent resource "

release_mem_region() has been changed to be called in each
PAGES_PER_SECTION by commit de7f0cba9678 ("memory hotplug: release
memory regions in PAGES_PER_SECTION chunks").  Because powerpc registers
iomem_resource in each PAGES_PER_SECTION chunk.  But when I hot add
memory on x86 box, iomem_resource is register in each _CRS not
PAGES_PER_SECTION chunk.  So x86 box unregisters iomem_resource.

The patch fixes the problem.

Signed-off-by: Yasuaki Ishimatsu 
Cc: David Rientjes 
Cc: Jiang Liu 
Cc: Len Brown 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Christoph Lameter 
Cc: Minchan Kim 
Cc: Andrew Morton 
Cc: KOSAKI Motohiro 
Cc: Wen Congyang 
Cc: Dave Hansen 
Cc: Nathan Fontenot 
Cc: Badari Pulavarty 
Cc: Yasunori Goto 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds