[PATCH 0/2] Add option to disable ACPI Memory Hotplug

[PATCH 0/2] Add option to disable ACPI Memory Hotplug

[Prarit Bhargava]

This patchset adds the ability for the user to disable ACPI Memory Hotplug
by adding "acpi_no_memhotplug" as a kernel paramaeter, and disables
ACPI Memory Hotplug by default when the memmap=exactmap and mem=X parameters
are used.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>=50%)
Cc: x86@kernel.org
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linn Crosetto <linn@hp.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: kosaki.motohiro@gmail.com
Cc: dyoung@redhat.com
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-acpi@vger.kernel.org
Cc: linux-mm@kvack.org

Prarit Bhargava (2):
  acpi memory hotplug, add parameter to disable memory hotplug [v2]
  x86, e820 disable ACPI Memory Hotplug if memory mapping is specified
    by user

 Documentation/kernel-parameters.txt |    3 +++
 arch/x86/kernel/e820.c              |    8 +++++++-
 drivers/acpi/acpi_memhotplug.c      |   17 +++++++++++++++++
 include/linux/memory_hotplug.h      |    3 +++
 4 files changed, 30 insertions(+), 1 deletion(-)

-- 
1.7.9.3

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[PATCH 1/2] acpi memory hotplug, add parameter to disable memory hotplug

[Prarit Bhargava]

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 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

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>=50%)
Cc: x86@kernel.org
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linn Crosetto <linn@hp.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: kosaki.motohiro@gmail.com
Cc: dyoung@redhat.com
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-acpi@vger.kernel.org
Cc: linux-mm@kvack.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..41374f9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2117,6 +2117,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 
 	nomce		[X86-32] Machine Check Exception
 
+	acpi_no_memhotplug [ACPI] Disable memory hotplug.  Useful for kexec
+			   and kdump kernels.
+
 	nomfgpt		[X86-32] Disable Multi-Function General Purpose
 			Timer usage (for AMD Geode machines).
 
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 551dad7..4a0fa94 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 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);
-- 
1.7.9.3

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[PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user

[Prarit Bhargava]

kdump uses memmap=exactmap and mem=X values to configure the memory
mapping for the kdump kernel.  If memory is hotadded during the boot of
the kdump kernel it is possible that the page tables for the new memory
cause the kdump kernel to run out of memory.

Since the user has specified a specific mapping ACPI Memory Hotplug should be
disabled in this case.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>=50%)
Cc: x86@kernel.org
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linn Crosetto <linn@hp.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: kosaki.motohiro@gmail.com
Cc: dyoung@redhat.com
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-acpi@vger.kernel.org
Cc: linux-mm@kvack.org
---
 arch/x86/kernel/e820.c         |    8 +++++++-
 drivers/acpi/acpi_memhotplug.c |    7 ++++++-
 include/linux/memory_hotplug.h |    3 +++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 174da5f..dc1191f 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -20,6 +20,7 @@
 #include <linux/firmware-map.h>
 #include <linux/memblock.h>
 #include <linux/sort.h>
+#include <linux/memory_hotplug.h>
 
 #include <asm/e820.h>
 #include <asm/proto.h>
@@ -880,15 +881,20 @@ static int __init parse_memmap_one(char *p)
 
 	return *p == '\0' ? 0 : -EINVAL;
 }
+
 static int __init parse_memmap_opt(char *str)
 {
+	int ret;
+
 	while (str) {
 		char *k = strchr(str, ',');
 
 		if (k)
 			*k++ = 0;
 
-		parse_memmap_one(str);
+		ret = parse_memmap_one(str);
+		if (!ret)
+			set_acpi_no_memhotplug();
 		str = k;
 	}
 
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index 4a0fa94..48b9267 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -363,6 +363,11 @@ static void acpi_memory_device_remove(struct acpi_device *device)
 
 static bool acpi_no_memhotplug;
 
+void set_acpi_no_memhotplug(void)
+{
+	acpi_no_memhotplug = true;
+}
+
 void __init acpi_memory_hotplug_init(void)
 {
 	if (acpi_no_memhotplug)
@@ -373,7 +378,7 @@ void __init acpi_memory_hotplug_init(void)
 
 static int __init disable_acpi_memory_hotplug(char *str)
 {
-	acpi_no_memhotplug = true;
+	set_acpi_no_memhotplug();
 	return 1;
 }
 __setup("acpi_no_memhotplug", disable_acpi_memory_hotplug);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 4ca3d95..80f5a23 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -12,6 +12,9 @@ struct pglist_data;
 struct mem_section;
 struct memory_block;
 
+/* set flag to disable ACPI memory hotplug */
+extern void set_acpi_no_memhotplug(void);
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 
 /*
-- 
1.7.9.3

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Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user

[Prarit Bhargava]

On 01/10/2014 01:46 PM, Prarit Bhargava wrote:
> kdump uses memmap=exactmap and mem=X values to configure the memory
> mapping for the kdump kernel.  If memory is hotadded during the boot of
> the kdump kernel it is possible that the page tables for the new memory
> cause the kdump kernel to run out of memory.
> 
> Since the user has specified a specific mapping ACPI Memory Hotplug should be
> disabled in this case.
> 

Noticed a bug in this.  Will repost a new version shortly.

P.

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