Message-ID: <1437311.bF4k07FdsN@vostro.rjw.lan>
Date:	Wed, 15 Jan 2014 14:47:49 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Prarit Bhargava <prarit@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Vivek Goyal <vgoyal@...hat.com>,
	Len Brown <lenb@...nel.org>, kosaki.motohiro@...il.com,
	dyoung@...hat.com, linux-acpi@...r.kernel.org,
	kexec@...ts.infradead.org
Subject: Re: [PATCH] acpi memory hotplug, add parameter to disable memory hotplug [v4]

On Wednesday, January 15, 2014 07:34:44 AM Prarit Bhargava wrote:
> When booting a kexec/kdump kernel on a system that has specific memory hotplug
> regions the boot will fail with warnings like:

Next time, can you please remove timestamps from dmesg output in
patch changelogs, unless those timestamps are relevant for the bug
description?

> [    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 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.
> 
> [v2]: changed acpi_no_memhotplug to bool
> [v3]: cleaned up Documentation/kernel-parameters.txt
> [v4]: add __initdata to acpi_no_memhotplug

If that's the only difference, I guess the previous ACKs etc. still apply?

Rafael


> Signed-off-by: Prarit Bhargava <prarit@...hat.com>
> Cc: Vivek Goyal <vgoyal@...hat.com>
> Cc: Len Brown <lenb@...nel.org>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: kosaki.motohiro@...il.com
> Cc: dyoung@...hat.com
> Cc: linux-acpi@...r.kernel.org
> Cc: kexec@...ts.infradead.org
> ---
>  Documentation/kernel-parameters.txt |    3 +++
>  drivers/acpi/acpi_memhotplug.c      |   12 ++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index b9e9bd8..ea93f75 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -343,6 +343,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			no: ACPI OperationRegions are not marked as reserved,
>  			no further checks are performed.
>  
> +	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kexec
> +			   and kdump kernels.
> +
>  	add_efi_memmap	[EFI; X86] Include EFI memory map in
>  			kernel's map of available physical RAM.
>  
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 551dad7..383cd80 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -361,7 +361,19 @@ static void acpi_memory_device_remove(struct acpi_device *device)
>  	acpi_memory_device_free(mem_device);
>  }
>  
> +static bool __initdata acpi_no_memhotplug;
> +
>  void __init acpi_memory_hotplug_init(void)
>  {
> +	if (acpi_no_memhotplug)
> +		return;
> +
>  	acpi_scan_add_handler_with_hotplug(&memory_device_handler, "memory");
>  }
> +
> +static int __init disable_acpi_memory_hotplug(char *str)
> +{
> +	acpi_no_memhotplug = true;
> +	return 1;
> +}
> +__setup("acpi_no_memhotplug", disable_acpi_memory_hotplug);
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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