Fix a bug where a kernel warning is triggered when performing a memory
hotplug on ppc64. This warning may also occur on any architecture that
uses the memory_probe_store interface.
WARNING: at drivers/base/memory.c:200
CPU: 9 PID: 13042 Comm: systemd-udevd Not tainted 4.4.0-rc4-00113-g0bd0f1e-dirty #7
NIP [c00000000055e034] pages_correctly_reserved+0x134/0x1b0
LR [c00000000055e7f8] memory_subsys_online+0x68/0x140
Call Trace:
memory_subsys_online+0x68/0x140
device_online+0xb4/0x120
store_mem_state+0xb0/0x180
dev_attr_store+0x34/0x60
sysfs_kf_write+0x64/0xa0
kernfs_fop_write+0x17c/0x1e0
__vfs_write+0x40/0x160
vfs_write+0xb8/0x200
SyS_write+0x60/0x110
system_call+0x38/0xd0
The warning is triggered because there is a udev rule that automatically
tries to online memory after it has been added. The udev rule varies
from distro to distro, but will generally look something like:
SUBSYSTEM=="memory", ACTION=="add", ATTR{state}=="offline", ATTR{state}="online"
On any architecture that uses memory_probe_store to reserve memory, the
udev rule will be triggered after the first section of the block is
reserved and will subsequently attempt to online the entire block,
interrupting the memory reservation process and causing the warning.
This patch modifies memory_probe_store to add a block of memory with a
single call to add_memory as opposed to looping through and adding each
section individually. A single call to add_memory is protected by the
mem_hotplug mutex which will prevent the udev rule from onlining memory
until the reservation of the entire block is complete.
Signed-off-by: John Allen <jallen@linux.vnet.ibm.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cb5490a5ee