On Thu, Jan 09, 2014 at 02:10:26PM +0100, Rafael J. Wysocki wrote: > On Wednesday, January 08, 2014 05:11:48 PM Toshi Kani wrote: > > On Thu, 2014-01-09 at 00:07 +0100, Rafael J. Wysocki wrote: > > > On Wednesday, January 08, 2014 10:58:29 AM Vivek Goyal wrote: > > > > On Wed, Jan 08, 2014 at 11:26:43PM +0800, Baoquan wrote: > > > > > > > > [..] > > > > > [ 1.592222] acpi PNP0A03:03: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge. > > > > > [ 1.605045] PCI host bridge to bus 0000:ff > > > > > [ 1.609615] pci_bus 0000:ff: root bus resource [bus ff] > > > > > [ 1.632117] System RAM resource [mem 0x01000000-0x7bffffff] cannot be added > > > > > [ 1.639892] init_memory_mapping: [mem 0x100000000-0x87fffffff] > > > > > [ 1.717793] swapper/0: page allocation failure: order:9, mode:0x84d0 > > > > > [ 1.724884] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-59.el7.x86_64 #1 > > > > > [ 1.732842] Hardware name: QCI QSSC-S4R/QSSC-S4R, BIOS QSSC-S4R.QCI.01.00.S001.032520101647 03/25/2010 > > > > > [ 1.743224] 0000000000000000 ffff8800339878c8 ffffffff815b64ad ffff880033987950 > > > > > [ 1.751513] ffffffff8113a980 ffff88003673ab28 00000000000001fe 0000000000000001 > > > > > [ 1.759804] ffff880000000040 ffffffff810bc28a 0000000000000000 0000000000000200 > > > > > [ 1.768096] Call Trace: [348/1928] > > > > > [ 1.770834] [<ffffffff815b64ad>] dump_stack+0x19/0x1b > > > > > [ 1.776561] [<ffffffff8113a980>] warn_alloc_failed+0xf0/0x160 > > > > > [ 1.783076] [<ffffffff810bc28a>] ? on_each_cpu_mask+0x2a/0x60 > > > > > [ 1.789581] [<ffffffff8113e92f>] __alloc_pages_nodemask+0x7ff/0xa00 > > > > > [ 1.796672] [<ffffffff815ada2c>] vmemmap_alloc_block+0x62/0xba > > > > > [ 1.803274] [<ffffffff815ada99>] vmemmap_alloc_block_buf+0x15/0x3b > > > > > [ 1.810263] [<ffffffff815ab8a6>] vmemmap_populate+0xb4/0x21b > > > > > [ 1.816673] [<ffffffff815adecd>] sparse_mem_map_populate+0x27/0x35 > > > > > [ 1.823665] [<ffffffff815ad8bf>] sparse_add_one_section+0x7a/0x185 > > > > > [ 1.830659] [<ffffffff8159b74f>] __add_pages+0xaf/0x240 > > > > > [ 1.836588] [<ffffffff81047359>] arch_add_memory+0x59/0xd0 > > > > > [ 1.842804] [<ffffffff8159ba89>] add_memory+0xb9/0x1b0 > > > > > [ 1.848638] [<ffffffff8132dd2c>] acpi_memory_device_add+0x18d/0x26d > > > > > [ 1.855728] [<ffffffff81303b91>] acpi_bus_device_attach+0x7d/0xcd > > > > > [ 1.862625] [<ffffffff8131d92d>] acpi_ns_walk_namespace+0xc8/0x17f > > > > > [ 1.869616] [<ffffffff81303b14>] ? acpi_bus_type_and_status+0x90/0x90 > > > > > [ 1.876896] [<ffffffff81303b14>] ? acpi_bus_type_and_status+0x90/0x90 > > > > > [ 1.884177] [<ffffffff8131de1c>] acpi_walk_namespace+0x95/0xc5 > > > > > [ 1.890780] [<ffffffff81304866>] acpi_bus_scan+0x8b/0x9d > > > > > [ 1.896805] [<ffffffff81a14a15>] acpi_scan_init+0x63/0x160 > > > > > [ 1.903021] [<ffffffff81a14830>] acpi_init+0x25d/0x2a6 > > > > > > > > So basically acpi thinks that some memory block is a hot plug memory > > > > and tries to add it. And that consumes lots of memory and we don't have > > > > that memory in second kernel. > > > > > > That's not exactly the case. What seems to happen is that there is an ACPI > > > memory object in the ACPI namespace and the ACPI memory hotplug driver > > > attempts to bind to it. That driver attempts to find removable memory blocks > > > associated with that object and to add them to the memory map. > > > > > > Why don't you simply append acpi=off to the kexec command line? That should > > > make the problem go away. > > > > Yes, that should work, but Baoquan's approach makes sense to me. When > > memmap=exactmap is specified, the kernel should ignore any memory > > information from the firmware. > > OK > > Baoquan, please modify your patch to get rid of the #ifdef CONFIG_X86 in > acpi_memory_hotplug_init(). For example, you can add a function returning true > if use_exactmap is set and false otherwise and make acpi_memory_hotplug_init() > call that function. Alternatively, you can define arch-independent > no_memory_hotplug (instead of use_exactmap) and set if for memmap=exactmap. > Prarit sent a patch to introduce no_memory_hotplug command line. I still think that memmap=exactmap does not necessarily mean that memory hotplug is disabled. What about mem= parameter. If somebody specifies mem=1G, should that mean there can not be any hotplugged memory. I think we should atleast define a new command line parameter to disable memory hotplug. After that users can specify both memmap=exactmap and "no_mem_hotplug" on command line and control the behavior of kernel. Thanks Vivek
