linux-toradex.git/include/linux/memory_hotplug.h, branch v5.10-rc3

mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System RAM resources

2020-10-16T18:11:18+00:00

Some add_memory*() users add memory in small, contiguous memory blocks.
Examples include virtio-mem, hyper-v balloon, and the XEN balloon.

This can quickly result in a lot of memory resources, whereby the actual
resource boundaries are not of interest (e.g., it might be relevant for
DIMMs, exposed via /proc/iomem to user space).  We really want to merge
added resources in this scenario where possible.

Let's provide a flag (MEMHP_MERGE_RESOURCE) to specify that a resource
either created within add_memory*() or passed via add_memory_resource()
shall be marked mergeable and merged with applicable siblings.

To implement that, we need a kernel/resource interface to mark selected
System RAM resources mergeable (IORESOURCE_SYSRAM_MERGEABLE) and trigger
merging.

Note: We really want to merge after the whole operation succeeded, not
directly when adding a resource to the resource tree (it would break
add_memory_resource() and require splitting resources again when the
operation failed - e.g., due to -ENOMEM).

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Reviewed-by: Pankaj Gupta 
Cc: Michal Hocko 
Cc: Dan Williams 
Cc: Jason Gunthorpe 
Cc: Kees Cook 
Cc: Ard Biesheuvel 
Cc: Thomas Gleixner 
Cc: "K. Y. Srinivasan" 
Cc: Haiyang Zhang 
Cc: Stephen Hemminger 
Cc: Wei Liu 
Cc: Boris Ostrovsky 
Cc: Juergen Gross 
Cc: Stefano Stabellini 
Cc: Roger Pau Monné 
Cc: Julien Grall 
Cc: Baoquan He 
Cc: Wei Yang 
Cc: Anton Blanchard 
Cc: Benjamin Herrenschmidt 
Cc: Christian Borntraeger 
Cc: Dave Jiang 
Cc: Eric Biederman 
Cc: Greg Kroah-Hartman 
Cc: Heiko Carstens 
Cc: Jason Wang 
Cc: Len Brown 
Cc: Leonardo Bras 
Cc: Libor Pechacek 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Nathan Lynch 
Cc: "Oliver O'Halloran" 
Cc: Paul Mackerras 
Cc: Pingfan Liu 
Cc: "Rafael J. Wysocki" 
Cc: Vasily Gorbik 
Cc: Vishal Verma 
Link: https://lkml.kernel.org/r/20200911103459.10306-6-david@redhat.com
Signed-off-by: Linus Torvalds

mm/memory_hotplug: prepare passing flags to add_memory() and friends

2020-10-16T18:11:18+00:00

We soon want to pass flags, e.g., to mark added System RAM resources.
mergeable.  Prepare for that.

This patch is based on a similar patch by Oscar Salvador:

https://lkml.kernel.org/r/20190625075227.15193-3-osalvador@suse.de

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Reviewed-by: Juergen Gross  # Xen related part
Reviewed-by: Pankaj Gupta 
Acked-by: Wei Liu 
Cc: Michal Hocko 
Cc: Dan Williams 
Cc: Jason Gunthorpe 
Cc: Baoquan He 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: "Rafael J. Wysocki" 
Cc: Len Brown 
Cc: Greg Kroah-Hartman 
Cc: Vishal Verma 
Cc: Dave Jiang 
Cc: "K. Y. Srinivasan" 
Cc: Haiyang Zhang 
Cc: Stephen Hemminger 
Cc: Wei Liu 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: David Hildenbrand 
Cc: "Michael S. Tsirkin" 
Cc: Jason Wang 
Cc: Boris Ostrovsky 
Cc: Stefano Stabellini 
Cc: "Oliver O'Halloran" 
Cc: Pingfan Liu 
Cc: Nathan Lynch 
Cc: Libor Pechacek 
Cc: Anton Blanchard 
Cc: Leonardo Bras 
Cc: Ard Biesheuvel 
Cc: Eric Biederman 
Cc: Julien Grall 
Cc: Kees Cook 
Cc: Roger Pau Monné 
Cc: Thomas Gleixner 
Cc: Wei Yang 
Link: https://lkml.kernel.org/r/20200911103459.10306-5-david@redhat.com
Signed-off-by: Linus Torvalds

mm/memory_hotplug: guard more declarations by CONFIG_MEMORY_HOTPLUG

2020-10-16T18:11:18+00:00

We soon want to pass flags via a new type to add_memory() and friends.
That revealed that we currently don't guard some declarations by
CONFIG_MEMORY_HOTPLUG.

While some definitions could be moved to different places, let's keep it
minimal for now and use CONFIG_MEMORY_HOTPLUG for all functions only
compiled with CONFIG_MEMORY_HOTPLUG.

Wrap sparse_decode_mem_map() into CONFIG_MEMORY_HOTPLUG, it's only called
from CONFIG_MEMORY_HOTPLUG code.

While at it, remove allow_online_pfn_range(), which is no longer around,
and mhp_notimplemented(), which is unused.

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Cc: Michal Hocko 
Cc: Dan Williams 
Cc: Pankaj Gupta 
Cc: Baoquan He 
Cc: Wei Yang 
Cc: Anton Blanchard 
Cc: Ard Biesheuvel 
Cc: Benjamin Herrenschmidt 
Cc: Boris Ostrovsky 
Cc: Christian Borntraeger 
Cc: Dave Jiang 
Cc: Eric Biederman 
Cc: Greg Kroah-Hartman 
Cc: Haiyang Zhang 
Cc: Heiko Carstens 
Cc: Jason Gunthorpe 
Cc: Jason Wang 
Cc: Juergen Gross 
Cc: Julien Grall 
Cc: Kees Cook 
Cc: "K. Y. Srinivasan" 
Cc: Len Brown 
Cc: Leonardo Bras 
Cc: Libor Pechacek 
Cc: Michael Ellerman 
Cc: "Michael S. Tsirkin" 
Cc: Nathan Lynch 
Cc: "Oliver O'Halloran" 
Cc: Paul Mackerras 
Cc: Pingfan Liu 
Cc: "Rafael J. Wysocki" 
Cc: Roger Pau Monné 
Cc: Stefano Stabellini 
Cc: Stephen Hemminger 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Vishal Verma 
Cc: Wei Liu 
Link: https://lkml.kernel.org/r/20200911103459.10306-4-david@redhat.com
Signed-off-by: Linus Torvalds

mm: pass migratetype into memmap_init_zone() and move_pfn_range_to_zone()

2020-10-16T18:11:17+00:00

On the memory onlining path, we want to start with MIGRATE_ISOLATE, to
un-isolate the pages after memory onlining is complete.  Let's allow
passing in the migratetype.

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Reviewed-by: Oscar Salvador 
Acked-by: Michal Hocko 
Cc: Wei Yang 
Cc: Baoquan He 
Cc: Pankaj Gupta 
Cc: Tony Luck 
Cc: Fenghua Yu 
Cc: Logan Gunthorpe 
Cc: Dan Williams 
Cc: Mike Rapoport 
Cc: "Matthew Wilcox (Oracle)" 
Cc: Michel Lespinasse 
Cc: Charan Teja Reddy 
Cc: Mel Gorman 
Link: https://lkml.kernel.org/r/20200819175957.28465-10-david@redhat.com
Signed-off-by: Linus Torvalds

mm/page_alloc: simplify __offline_isolated_pages()

2020-10-16T18:11:17+00:00

offline_pages() is the only user.  __offline_isolated_pages() never gets
called with ranges that contain memory holes and we no longer care about
the return value.  Drop the return value handling and all pfn_valid()
checks.

Update the documentation.

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Reviewed-by: Oscar Salvador 
Acked-by: Michal Hocko 
Cc: Wei Yang 
Cc: Baoquan He 
Cc: Pankaj Gupta 
Cc: Charan Teja Reddy 
Cc: Dan Williams 
Cc: Fenghua Yu 
Cc: Logan Gunthorpe 
Cc: "Matthew Wilcox (Oracle)" 
Cc: Mel Gorman 
Cc: Mel Gorman 
Cc: Michel Lespinasse 
Cc: Mike Rapoport 
Cc: Tony Luck 
Link: https://lkml.kernel.org/r/20200819175957.28465-5-david@redhat.com
Signed-off-by: Linus Torvalds

mm/memory_hotplug: introduce default phys_to_target_node() implementation

2020-10-14T01:38:27+00:00

In preparation to set a fallback value for dev_dax->target_node, introduce
generic fallback helpers for phys_to_target_node()

A generic implementation based on node-data or memblock was proposed, but
as noted by Mike:

    "Here again, I would prefer to add a weak default for
     phys_to_target_node() because the "generic" implementation is not really
     generic.

     The fallback to reserved ranges is x86 specfic because on x86 most of
     the reserved areas is not in memblock.memory. AFAIK, no other
     architecture does this."

The info message in the generic memory_add_physaddr_to_nid()
implementation is fixed up to properly reflect that
memory_add_physaddr_to_nid() communicates "online" node info and
phys_to_target_node() indicates "target / to-be-onlined" node info.

[akpm@linux-foundation.org: fix CONFIG_MEMORY_HOTPLUG=n build]
  Link: https://lkml.kernel.org/r/202008252130.7YrHIyMI%25lkp@intel.com

Signed-off-by: Dan Williams 
Signed-off-by: Andrew Morton 
Cc: David Hildenbrand 
Cc: Mike Rapoport 
Cc: Jia He 
Cc: Andy Lutomirski 
Cc: Ard Biesheuvel 
Cc: Benjamin Herrenschmidt 
Cc: Ben Skeggs 
Cc: Borislav Petkov 
Cc: Brice Goglin 
Cc: Catalin Marinas 
Cc: Daniel Vetter 
Cc: Dave Hansen 
Cc: Dave Jiang 
Cc: David Airlie 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Ira Weiny 
Cc: Jason Gunthorpe 
Cc: Jeff Moyer 
Cc: Joao Martins 
Cc: Jonathan Cameron 
Cc: Michael Ellerman 
Cc: Paul Mackerras 
Cc: Pavel Tatashin 
Cc: Peter Zijlstra 
Cc: Rafael J. Wysocki 
Cc: Thomas Gleixner 
Cc: Tom Lendacky 
Cc: Vishal Verma 
Cc: Wei Yang 
Cc: Will Deacon 
Cc: Ard Biesheuvel 
Cc: Bjorn Helgaas 
Cc: Boris Ostrovsky 
Cc: Hulk Robot 
Cc: Jason Yan 
Cc: "Jérôme Glisse" 
Cc: Juergen Gross 
Cc: kernel test robot 
Cc: Randy Dunlap 
Cc: Stefano Stabellini 
Cc: Vivek Goyal 
Link: https://lkml.kernel.org/r/159643097768.4062302.3135192588966888630.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Linus Torvalds

Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

2020-06-10T20:42:09+00:00

Pull virtio updates from Michael Tsirkin:

 - virtio-mem: paravirtualized memory hotplug

 - support doorbell mapping for vdpa

 - config interrupt support in ifc

 - fixes all over the place

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (40 commits)
  vhost/test: fix up after API change
  virtio_mem: convert device block size into 64bit
  virtio-mem: drop unnecessary initialization
  ifcvf: implement config interrupt in IFCVF
  vhost: replace -1 with VHOST_FILE_UNBIND in ioctls
  vhost_vdpa: Support config interrupt in vdpa
  ifcvf: ignore continuous setting same status value
  virtio-mem: Don't rely on implicit compiler padding for requests
  virtio-mem: Try to unplug the complete online memory block first
  virtio-mem: Use -ETXTBSY as error code if the device is busy
  virtio-mem: Unplug subblocks right-to-left
  virtio-mem: Drop manual check for already present memory
  virtio-mem: Add parent resource for all added "System RAM"
  virtio-mem: Better retry handling
  virtio-mem: Offline and remove completely unplugged memory blocks
  mm/memory_hotplug: Introduce offline_and_remove_memory()
  virtio-mem: Allow to offline partially unplugged memory blocks
  mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE
  virtio-mem: Paravirtualized memory hotunplug part 2
  virtio-mem: Paravirtualized memory hotunplug part 1
  ...

mm/memory_hotplug: introduce add_memory_driver_managed()

2020-06-05T02:06:23+00:00

Patch series "mm/memory_hotplug: Interface to add driver-managed system
ram", v4.

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].

[1] https://lkml.kernel.org/r/20200429160803.109056-1-david@redhat.com
[2] https://lkml.kernel.org/r/20200430102908.10107-1-david@redhat.com

This patch (of 3):

Some device drivers rely on memory they managed to not get added to the
initial (firmware) memmap as system RAM - so it's not used as initial
system RAM by the kernel and the driver is under control.  While this is
the case during cold boot and after a reboot, kexec is not aware of that
and might add such memory to the initial (firmware) memmap of the kexec
kernel.  We need ways to teach kernel and userspace that this system ram
is different.

For example, dax/kmem allows to decide at runtime if persistent memory is
to be used as system ram.  Another future user is virtio-mem, which has to
coordinate with its hypervisor to deal with inaccessible parts within
memory resources.

We want to let users in the kernel (esp. kexec) but also user space
(esp. kexec-tools) know that this memory has different semantics and
needs to be handled differently:
1. Don't create entries in /sys/firmware/memmap/
2. Name the memory resource "System RAM ($DRIVER)" (exposed via
   /proc/iomem) ($DRIVER might be "kmem", "virtio_mem").
3. Flag the memory resource IORESOURCE_MEM_DRIVER_MANAGED

/sys/firmware/memmap/ [1] represents the "raw firmware-provided memory
map" because "on most architectures that firmware-provided memory map is
modified afterwards by the kernel itself".  The primary user is kexec on
x86-64.  Since commit d96ae5309165 ("memory-hotplug: create
/sys/firmware/memmap entry for new memory"), we add all hotplugged memory
to that firmware memmap - which makes perfect sense for traditional memory
hotplug on x86-64, where real HW will also add hotplugged DIMMs to the
firmware memmap.  We replicate what the "raw firmware-provided memory map"
looks like after hot(un)plug.

To keep things simple, let the user provide the full resource name instead
of only the driver name - this way, we don't have to manually
allocate/craft strings for memory resources.  Also use the resource name
to make decisions, to avoid passing additional flags.  In case the name
isn't "System RAM", it's special.

We don't have to worry about firmware_map_remove() on the removal path.
If there is no entry, it will simply return with -EINVAL.

We'll adapt dax/kmem in a follow-up patch.

[1] https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-memmap

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Acked-by: Pankaj Gupta 
Cc: Michal Hocko 
Cc: Pankaj Gupta 
Cc: Wei Yang 
Cc: Baoquan He 
Cc: Dave Hansen 
Cc: Eric Biederman 
Cc: Pavel Tatashin 
Cc: Dan Williams 
Link: http://lkml.kernel.org/r/20200508084217.9160-1-david@redhat.com
Link: http://lkml.kernel.org/r/20200508084217.9160-3-david@redhat.com
Signed-off-by: Linus Torvalds

mm/memory_hotplug: remove is_mem_section_removable()

2020-06-05T02:06:23+00:00

Fortunately, all users of is_mem_section_removable() are gone.  Get rid of
it, including some now unnecessary functions.

Signed-off-by: David Hildenbrand 
Signed-off-by: Andrew Morton 
Reviewed-by: Wei Yang 
Reviewed-by: Baoquan He 
Acked-by: Michal Hocko 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Oscar Salvador 
Link: http://lkml.kernel.org/r/20200407135416.24093-3-david@redhat.com
Signed-off-by: Linus Torvalds

mm/memory_hotplug: Introduce offline_and_remove_memory()

2020-06-04T19:36:52+00:00

virtio-mem wants to offline and remove a memory block once it unplugged
all subblocks (e.g., using alloc_contig_range()). Let's provide
an interface to do that from a driver. virtio-mem already supports to
offline partially unplugged memory blocks. Offlining a fully unplugged
memory block will not require to migrate any pages. All unplugged
subblocks are PageOffline() and have a reference count of 0 - so
offlining code will simply skip them.

All we need is an interface to offline and remove the memory from kernel
module context, where we don't have access to the memory block devices
(esp. find_memory_block() and device_offline()) and the device hotplug
lock.

To keep things simple, allow to only work on a single memory block.

Acked-by: Michal Hocko 
Tested-by: Pankaj Gupta 
Acked-by: Andrew Morton 
Cc: Andrew Morton 
Cc: David Hildenbrand 
Cc: Oscar Salvador 
Cc: Michal Hocko 
Cc: Pavel Tatashin 
Cc: Wei Yang 
Cc: Dan Williams 
Cc: Qian Cai 
Signed-off-by: David Hildenbrand 
Link: https://lore.kernel.org/r/20200507140139.17083-9-david@redhat.com
Signed-off-by: Michael S. Tsirkin