From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, linux-nvdimm@lists.01.org,
kexec@lists.infradead.org,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
David Hildenbrand <david@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Wei Yang <richard.weiyang@gmail.com>, Baoquan He <bhe@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eric Biederman <ebiederm@xmission.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: [PATCH v3 3/3] device-dax: Add memory via add_memory_driver_managed()
Date: Mon, 4 May 2020 21:02:27 +0200 [thread overview]
Message-ID: <20200504190227.18269-4-david@redhat.com> (raw)
In-Reply-To: <20200504190227.18269-1-david@redhat.com>
Currently, when adding memory, we create entries in /sys/firmware/memmap/
as "System RAM". This 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'd kernel and
can no longer be reconfigured. This is not what happens during a real
reboot.
Let's add our memory via add_memory_driver_managed() now, so we won't
create entries in /sys/firmware/memmap/ and indicate the memory as
"System RAM (kmem)" in /proc/iomem. This allows everybody (especially
kexec-tools) to identify that this memory is special and has to be treated
differently than ordinary (hotplugged) System RAM.
Before configuring the namespace:
[root@localhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-33fffffff : namespace0.0
3280000000-32ffffffff : PCI Bus 0000:00
After configuring the namespace:
[root@localhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
148200000-33fffffff : dax0.0
3280000000-32ffffffff : PCI Bus 0000:00
After loading kmem before this change:
[root@localhost ~]# 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 loading kmem after this change:
[root@localhost ~]# cat /proc/iomem
...
140000000-33fffffff : Persistent Memory
140000000-1481fffff : namespace0.0
150000000-33fffffff : dax0.0
150000000-33fffffff : System RAM (kmem)
3280000000-32ffffffff : PCI Bus 0000:00
After a proper reboot:
[root@localhost ~]# 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@localhost ~]# 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@localhost ~]# 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. Changing the resource name
won't have an impact.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/dax/kmem.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 3d0a7e702c94..5a645a24e359 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -65,7 +65,13 @@ 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));
+ /*
+ * Ensure that future kexec'd kernels will not treat this as RAM
+ * automatically.
+ */
+ rc = add_memory_driver_managed(numa_node, new_res->start,
+ resource_size(new_res),
+ "System RAM (kmem)");
if (rc) {
release_resource(new_res);
kfree(new_res);
--
2.25.3
next prev parent reply other threads:[~2020-05-04 19:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-04 19:02 [PATCH v3 0/3] mm/memory_hotplug: Interface to add driver-managed system ram David Hildenbrand
2020-05-04 19:02 ` [PATCH v3 1/3] mm/memory_hotplug: Introduce add_memory_device_managed() David Hildenbrand
2020-05-06 13:57 ` Pankaj Gupta
2020-05-06 14:19 ` David Hildenbrand
2020-05-04 19:02 ` [PATCH v3 2/3] kexec_file: Don't place kexec images on IORESOURCE_MEM_DRIVER_MANAGED David Hildenbrand
2020-05-04 19:02 ` David Hildenbrand [this message]
2020-05-06 13:55 ` [PATCH v3 3/3] device-dax: Add memory via add_memory_driver_managed() Pankaj Gupta
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