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Date: Thu, 30 Apr 2020 12:29:08 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org, virtio-dev@...ts.oasis-open.org,
virtualization@...ts.linux-foundation.org,
linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
linux-nvdimm@...ts.01.org, linux-hyperv@...r.kernel.org,
linux-s390@...r.kernel.org, xen-devel@...ts.xenproject.org,
Michal Hocko <mhocko@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
"Michael S . Tsirkin" <mst@...hat.com>,
David Hildenbrand <david@...hat.com>,
Michal Hocko <mhocko@...e.com>,
Pankaj Gupta <pankaj.gupta.linux@...il.com>,
Wei Yang <richard.weiyang@...il.com>,
Baoquan He <bhe@...hat.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Eric Biederman <ebiederm@...ssion.com>,
Pavel Tatashin <pasha.tatashin@...een.com>,
Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH v2 3/3] device-dax: Add system ram (add_memory()) with MHP_NO_FIRMWARE_MEMMAP
Currently, when adding memory, we create entries in /sys/firmware/memmap/
as "System RAM". This does not reflect the reality and will lead to
kexec-tools to add that memory to the fixed-up initial memmap for a
kexec kernel (loaded via kexec_load()). The memory will be considered
initial System RAM by the kexec kernel.
We should let the kexec kernel decide how to use that memory - just as
we do during an ordinary reboot.
Before configuring the namespace:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-33fffffff : namespace0.0
3280000000-32ffffffff : PCI Bus 0000:00
After configuring the namespace:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
148200000-33fffffff : dax0.0
3280000000-32ffffffff : PCI Bus 0000:00
After loading kmem:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
150000000-33fffffff : dax0.0
150000000-33fffffff : System RAM
3280000000-32ffffffff : PCI Bus 0000:00
After a proper reboot:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
148200000-33fffffff : dax0.0
3280000000-32ffffffff : PCI Bus 0000:00
Within the kexec kernel before this change:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
150000000-33fffffff : System RAM
3280000000-32ffffffff : PCI Bus 0000:00
Within the kexec kernel after this change:
[root@...alhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
148200000-33fffffff : dax0.0
3280000000-32ffffffff : PCI Bus 0000:00
/sys/firmware/memmap/ before this change:
0000000000000000-000000000009fc00 (System RAM)
000000000009fc00-00000000000a0000 (Reserved)
00000000000f0000-0000000000100000 (Reserved)
0000000000100000-00000000bffdf000 (System RAM)
00000000bffdf000-00000000c0000000 (Reserved)
00000000feffc000-00000000ff000000 (Reserved)
00000000fffc0000-0000000100000000 (Reserved)
0000000100000000-0000000140000000 (System RAM)
0000000150000000-0000000340000000 (System RAM)
/sys/firmware/memmap/ after a proper reboot:
0000000000000000-000000000009fc00 (System RAM)
000000000009fc00-00000000000a0000 (Reserved)
00000000000f0000-0000000000100000 (Reserved)
0000000000100000-00000000bffdf000 (System RAM)
00000000bffdf000-00000000c0000000 (Reserved)
00000000feffc000-00000000ff000000 (Reserved)
00000000fffc0000-0000000100000000 (Reserved)
0000000100000000-0000000140000000 (System RAM)
/sys/firmware/memmap/ after this change:
0000000000000000-000000000009fc00 (System RAM)
000000000009fc00-00000000000a0000 (Reserved)
00000000000f0000-0000000000100000 (Reserved)
0000000000100000-00000000bffdf000 (System RAM)
00000000bffdf000-00000000c0000000 (Reserved)
00000000feffc000-00000000ff000000 (Reserved)
00000000fffc0000-0000000100000000 (Reserved)
0000000100000000-0000000140000000 (System RAM)
kexec-tools already seem to basically ignore any System RAM that's not
on top level when searching for areas to place kexec images - but also
for determining crash areas to dump via kdump. This behavior is not
changed by this patch. kexec-tools probably has to be fixed to also
include this memory in system dumps.
Note: kexec_file_load() does the right thing already within the kernel.
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
Cc: Wei Yang <richard.weiyang@...il.com>
Cc: Baoquan He <bhe@...hat.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Eric Biederman <ebiederm@...ssion.com>
Cc: Pavel Tatashin <pasha.tatashin@...een.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
drivers/dax/kmem.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index e159184e0ba0..929823a79816 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -65,7 +65,8 @@ int dev_dax_kmem_probe(struct device *dev)
new_res->flags = IORESOURCE_SYSTEM_RAM;
new_res->name = dev_name(dev);
- rc = add_memory(numa_node, new_res->start, resource_size(new_res), 0);
+ rc = add_memory(numa_node, new_res->start, resource_size(new_res),
+ MHP_NO_FIRMWARE_MEMMAP);
if (rc) {
release_resource(new_res);
kfree(new_res);
--
2.25.3
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