Re: [PATCH v4 00/13] migrate/ram: Fix resizing RAM blocks while migrating

[David Hildenbrand <david@redhat.com>]

On 21.04.20 10:52, David Hildenbrand wrote:
> Basically a resend. Who's the lucky winner to pick this up for 5.1? :)
> 

Gentle ping, I have loads of patches in my backlog, and it does not seem
to get any shorter.

> ---
> 
> This is the follow up of
>     "[PATCH RFC] memory: Don't allow to resize RAM while migrating" [1]
> 
> This series contains some (slightly modified) patches also contained in:
>     "[PATCH v2 fixed 00/16] Ram blocks with resizable anonymous allocations
>      under POSIX" [2]
> That series will be based on this series. The last patch (#13) in this
> series could be moved to the other series, but I decided to include it in
> here for now (similar context).
> 
> I realized that resizing RAM blocks while the guest is being migrated
> (precopy: resize while still running on the source, postcopy: resize
>  while already running on the target) is buggy. In case of precopy, we
> can simply cancel migration. Postcopy handling is more involved. Resizing
> can currently happen during a guest reboot, triggered by ACPI rebuilds.
> 
> Along with the fixes, some cleanups.
> 
> [1] https://lkml.kernel.org/r/20200213172016.196609-1-david@redhat.com
> [2] https://lkml.kernel.org/r/20200212134254.11073-1-david@redhat.com
> 
> v3 -> v4:
> - Rebased and retested
> - Added RBs
> 
> v2 -> v3:
> - Rebased on current master
> - Added RBs
> - "migration/ram: Tolerate partially changed mappings in postcopy code"
> -- Extended the comment for the uffdio unregister part.
> 
> v1 -> v2:
> - "util: vfio-helpers: Factor out and fix processing of existing ram
>    blocks"
> -- Stringify error
> - "migraton/ram: Handle RAM block resizes during precopy"
> -- Simplified check if we're migrating on the source
> - "exec: Relax range check in ram_block_discard_range()"
> -- Added to make discard during resizes actually work
> - "migration/ram: Discard new RAM when growing RAM blocks after
>    ram_postcopy_incoming_init()"
> -- Better checks if in the right postcopy mode.
> -- Better patch subject/description/comments
> - "migration/ram: Handle RAM block resizes during postcopy"
> -- Better comments
> -- Adapt to changed postcopy checks
> - "migrate/ram: Get rid of "place_source" in ram_load_postcopy()"
> -- Dropped, as broken
> - "migration/ram: Tolerate partially changed mappings in postcopy code"
> -- Better comment / description. Clarify that no implicit wakeup will
>    happen
> -- Warn on EINVAL (older kernels)
> -- Wake up any waiter explicitly
> 
> David Hildenbrand (13):
>   util: vfio-helpers: Factor out and fix processing of existing ram
>     blocks
>   stubs/ram-block: Remove stubs that are no longer needed
>   numa: Teach ram block notifiers about resizeable ram blocks
>   numa: Make all callbacks of ram block notifiers optional
>   migration/ram: Handle RAM block resizes during precopy
>   exec: Relax range check in ram_block_discard_range()
>   migration/ram: Discard RAM when growing RAM blocks after
>     ram_postcopy_incoming_init()
>   migration/ram: Simplify host page handling in ram_load_postcopy()
>   migration/ram: Consolidate variable reset after placement in
>     ram_load_postcopy()
>   migration/ram: Handle RAM block resizes during postcopy
>   migration/multifd: Print used_length of memory block
>   migration/ram: Use offset_in_ramblock() in range checks
>   migration/ram: Tolerate partially changed mappings in postcopy code
> 
>  exec.c                     |  25 +++++--
>  hw/core/numa.c             |  41 +++++++++--
>  hw/i386/xen/xen-mapcache.c |   7 +-
>  include/exec/cpu-common.h  |   1 +
>  include/exec/memory.h      |  10 +--
>  include/exec/ramblock.h    |  10 +++
>  include/exec/ramlist.h     |  13 ++--
>  migration/migration.c      |   9 ++-
>  migration/migration.h      |   1 +
>  migration/multifd.c        |   2 +-
>  migration/postcopy-ram.c   |  54 +++++++++++++-
>  migration/ram.c            | 144 ++++++++++++++++++++++++++++---------
>  stubs/ram-block.c          |  20 ------
>  target/i386/hax-mem.c      |   5 +-
>  target/i386/sev.c          |  18 ++---
>  util/vfio-helpers.c        |  41 ++++-------
>  16 files changed, 283 insertions(+), 118 deletions(-)
> 


-- 
Thanks,

David / dhildenb