Re: [PATCH] x86, acpi memory hotplug, add parameter to disable memoryhotplug

[Prarit Bhargava]

On 01/13/2014 05:17 PM, KOSAKI Motohiro wrote:
> On Mon, Jan 13, 2014 at 4:56 PM, Prarit Bhargava <prarit@xxxxxxxxxx> wrote:
>> When booting a kexec/kdump kernel on a system that has specific memory hotplug
>> regions the boot will fail with warnings like:
>>
>> [    2.939467] swapper/0: page allocation failure: order:9, mode:0x84d0
>> [    2.946564] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
>> 3.10.0-65.el7.x86_64 #1
>> [    2.954532] Hardware name: QCI QSSC-S4R/QSSC-S4R, BIOS
>> QSSC-S4R.QCI.01.00.S013.032920111005 03/29/2011
>> [    2.964926]  0000000000000000 ffff8800341bd8c8 ffffffff815bcc67
>> ffff8800341bd950
>> [    2.973224]  ffffffff8113b1a0 ffff880036339b00 0000000000000009
>> 00000000000084d0
>> [    2.981523]  ffff8800341bd950 ffffffff815b87ee 0000000000000000
>> 0000000000000200
>> [    2.989821] Call Trace:
>> [    2.992560]  [<ffffffff815bcc67>] dump_stack+0x19/0x1b
>> [    2.998300]  [<ffffffff8113b1a0>] warn_alloc_failed+0xf0/0x160
>> [    3.004817]  [<ffffffff815b87ee>] ?
>> __alloc_pages_direct_compact+0xac/0x196
>> [    3.012594]  [<ffffffff8113f14f>] __alloc_pages_nodemask+0x7ff/0xa00
>> [    3.019692]  [<ffffffff815b417c>] vmemmap_alloc_block+0x62/0xba
>> [    3.026303]  [<ffffffff815b41e9>] vmemmap_alloc_block_buf+0x15/0x3b
>> [    3.033302]  [<ffffffff815b1ff6>] vmemmap_populate+0xb4/0x21b
>> [    3.039718]  [<ffffffff815b461d>] sparse_mem_map_populate+0x27/0x35
>> [    3.046717]  [<ffffffff815b400f>] sparse_add_one_section+0x7a/0x185
>> [    3.053720]  [<ffffffff815a1e9f>] __add_pages+0xaf/0x240
>> [    3.059656]  [<ffffffff81047359>] arch_add_memory+0x59/0xd0
>> [    3.065877]  [<ffffffff815a21d9>] add_memory+0xb9/0x1b0
>> [    3.071713]  [<ffffffff81333b9c>] acpi_memory_device_add+0x18d/0x26d
>> [    3.078813]  [<ffffffff81309a01>] acpi_bus_device_attach+0x7d/0xcd
>> [    3.085719]  [<ffffffff8132379d>] acpi_ns_walk_namespace+0xc8/0x17f
>> [    3.092716]  [<ffffffff81309984>] ? acpi_bus_type_and_status+0x90/0x90
>> [    3.100004]  [<ffffffff81309984>] ? acpi_bus_type_and_status+0x90/0x90
>> [    3.107293]  [<ffffffff81323c8c>] acpi_walk_namespace+0x95/0xc5
>> [    3.113904]  [<ffffffff8130a6d6>] acpi_bus_scan+0x8b/0x9d
>> [    3.119933]  [<ffffffff81a2019a>] acpi_scan_init+0x63/0x160
>> [    3.126153]  [<ffffffff81a1ffb5>] acpi_init+0x25d/0x2a6
>> [    3.131987]  [<ffffffff81a1fd58>] ? acpi_sleep_proc_init+0x2a/0x2a
>> [    3.138889]  [<ffffffff810020e2>] do_one_initcall+0xe2/0x190
>> [    3.145210]  [<ffffffff819e20c4>] kernel_init_freeable+0x17c/0x207
>> [    3.152111]  [<ffffffff819e18d0>] ? do_early_param+0x88/0x88
>> [    3.158430]  [<ffffffff8159fea0>] ? rest_init+0x80/0x80
>> [    3.164264]  [<ffffffff8159feae>] kernel_init+0xe/0x180
>> [    3.170097]  [<ffffffff815cca2c>] ret_from_fork+0x7c/0xb0
>> [    3.176123]  [<ffffffff8159fea0>] ? rest_init+0x80/0x80
>> [    3.181956] Mem-Info:
>> [    3.184490] Node 0 DMA per-cpu:
>> [    3.188007] CPU    0: hi:    0, btch:   1 usd:   0
>> [    3.193353] Node 0 DMA32 per-cpu:
>> [    3.197060] CPU    0: hi:   42, btch:   7 usd:   0
>> [    3.202410] active_anon:0 inactive_anon:0 isolated_anon:0
>> [    3.202410]  active_file:0 inactive_file:0 isolated_file:0
>> [    3.202410]  unevictable:0 dirty:0 writeback:0 unstable:0
>> [    3.202410]  free:872 slab_reclaimable:13 slab_unreclaimable:1880
>> [    3.202410]  mapped:0 shmem:0 pagetables:0 bounce:0
>> [    3.202410]  free_cma:0
>>
>> because the system has run out of memory at boot time.  This occurs
>> because of the following sequence in the boot:
>>
>> Main kernel boots and sets E820 map.  The second kernel is booted with a
>> map generated by the kdump service using memmap= and memmap=exactmap.
>> These parameters are added to the kernel parameters of the kexec/kdump
>> kernel.   The kexec/kdump kernel has limited memory resources so as not
>> to severely impact the main kernel.
>>
>> The system then panics and the kdump/kexec kernel boots (which is a
>> completely new kernel boot).  During this boot ACPI is initialized and the
>> kernel (as can be seen above) traverses the ACPI namespace and finds an
>> entry for a memory device to be hotadded.
>>
>> ie)
>>
>> [    3.053720]  [<ffffffff815a1e9f>] __add_pages+0xaf/0x240
>> [    3.059656]  [<ffffffff81047359>] arch_add_memory+0x59/0xd0
>> [    3.065877]  [<ffffffff815a21d9>] add_memory+0xb9/0x1b0
>> [    3.071713]  [<ffffffff81333b9c>] acpi_memory_device_add+0x18d/0x26d
>> [    3.078813]  [<ffffffff81309a01>] acpi_bus_device_attach+0x7d/0xcd
>> [    3.085719]  [<ffffffff8132379d>] acpi_ns_walk_namespace+0xc8/0x17f
>> [    3.092716]  [<ffffffff81309984>] ? acpi_bus_type_and_status+0x90/0x90
>> [    3.100004]  [<ffffffff81309984>] ? acpi_bus_type_and_status+0x90/0x90
>> [    3.107293]  [<ffffffff81323c8c>] acpi_walk_namespace+0x95/0xc5
>> [    3.113904]  [<ffffffff8130a6d6>] acpi_bus_scan+0x8b/0x9d
>> [    3.119933]  [<ffffffff81a2019a>] acpi_scan_init+0x63/0x160
>> [    3.126153]  [<ffffffff81a1ffb5>] acpi_init+0x25d/0x2a6
>>
>> At this point the kernel adds page table information and the the kexec/kdump
>> kernel runs out of memory.
>>
>> This can also be reproduced with a "regular" kernel by using the
>> memmap=exactmap and mem=X parameters on the main kernel and booting.
>>
>> This patchset resolves the problem by adding a kernel parameter,
>> acpi_no_memhotplug, to disable ACPI memory hotplug.  ACPI memory hotplug
>> should also be disabled by default when a user specified a memory mapping with
>> "memmap=exactmap" or "mem=X".
>>
>> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
>> Cc: x86@xxxxxxxxxx
>> Cc: Len Brown <lenb@xxxxxxxxxx>
>> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
>> Cc: Linn Crosetto <linn@xxxxxx>
>> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
>> Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Toshi Kani <toshi.kani@xxxxxx>
>> Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
>> Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
>> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
>> Cc: kosaki.motohiro@xxxxxxxxx
>> Cc: dyoung@xxxxxxxxxx
>> Cc: Toshi Kani <toshi.kani@xxxxxx>
>> Cc: linux-acpi@xxxxxxxxxxxxxxx
>> Cc: linux-mm@xxxxxxxxx
> 
> I think we need a knob manually enable mem-hotplug when specify memmap. But
> it is another story.
> 
> Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>

As mentioned, self-NAK.  I have seen a system that I needed to specify
memmap=exactmap & had hotplug memory.  I will only keep the acpi_no_memhotplug
option in the next version of the patch.

P.
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