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

[KOSAKI Motohiro]

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>
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