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>,
Baoquan He <bhe@redhat.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eric Biederman <ebiederm@xmission.com>,
Michal Hocko <mhocko@suse.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Wei Yang <richard.weiyang@gmail.com>
Subject: [PATCH v3 0/3] mm/memory_hotplug: Interface to add driver-managed system ram
Date: Mon, 4 May 2020 21:02:24 +0200 [thread overview]
Message-ID: <20200504190227.18269-1-david@redhat.com> (raw)
Third time is the charm? Let's see ... :)
This is the follow up of [1]:
[PATCH v1 0/3] mm/memory_hotplug: Make virtio-mem play nicely with
kexec-tools
and [2]:
[PATCH v2 0/3] mm/memory_hotplug: Allow to not create firmware memmap
entries
kexec (via kexec_load()) can currently not properly handle memory added via
dax/kmem, and will have similar issues with virtio-mem. kexec-tools will
currently add all memory to the fixed-up initial firmware memmap. In case
of dax/kmem, this means that - in contrast to a proper reboot - how that
persistent memory will be used can no longer be configured by the kexec'd
kernel. In case of virtio-mem it will be harmful, because that memory
might contain inaccessible pieces that require coordination with hypervisor
first.
In both cases, we want to let the driver in the kexec'd kernel handle
detecting and adding the memory, like during an ordinary reboot.
Introduce add_memory_driver_managed(). More on the samentics are in patch
#1.
In the future, we might want to make this behavior configurable for
dax/kmem- either by configuring it in the kernel (which would then also
allow to configure kexec_file_load()) or in kexec-tools by also adding
"System RAM (kmem)" memory from /proc/iomem to the fixed-up initial
firmware memmap.
More on the motivation can be found in [1] and [2].
v2 -> v3:
- Don't use flags for add_memory() and friends, provide
add_memory_driver_managed() instead.
- Flag memory resources via IORESOURCE_MEM_DRIVER_MANAGED and handle them
in kexec.
- Name memory resources "System RAM ($DRIVER)", visible via /proc/iomem
- Added more details to the patch descriptions, especially regarding the
history of /sys/firmware/memmap
- Add a comment to the device-dax change. Dropped Dave's Ack as the
v1 -> v2:
- Don't change the resource name
- Rename the flag to MHP_NO_FIRMWARE_MEMMAP to reflect what it is doing
- Rephrase subjects/descriptions
- Use the flag for dax/kmem
[1] https://lkml.kernel.org/r/20200429160803.109056-1-david@redhat.com
[2] https://lkml.kernel.org/r/20200430102908.10107-1-david@redhat.com
David Hildenbrand (3):
mm/memory_hotplug: Introduce add_memory_device_managed()
kexec_file: Don't place kexec images on IORESOURCE_MEM_DRIVER_MANAGED
device-dax: Add memory via add_memory_driver_managed()
drivers/dax/kmem.c | 8 ++++-
include/linux/ioport.h | 1 +
include/linux/memory_hotplug.h | 2 ++
kernel/kexec_file.c | 5 +++
mm/memory_hotplug.c | 62 +++++++++++++++++++++++++++++++---
5 files changed, 73 insertions(+), 5 deletions(-)
--
2.25.3
next 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 David Hildenbrand [this message]
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 ` [PATCH v3 3/3] device-dax: Add memory via add_memory_driver_managed() David Hildenbrand
2020-05-06 13:55 ` Pankaj Gupta
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