Re: [PATCH 6/8] s390/mm: implement MEM_PHYS_ONLINE MEM_PHYS_OFFLINE memory notifiers

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 14.11.23 19:02, Sumanth Korikkar wrote:
Implement MEM_PHYS_ONLINE and MEM_PHYS_OFFLINE memory notifiers on s390

Implementation of MEM_PHYS_ONLINE Memory Notifier:
* Transition the memory block to an accessible/online state using the
   sclp assign command.
* Execute __add_pages() for the memory block, enabling a self-contained
   memory map range. For boot-time memory, vmemmap mapping is carried out
   through sparse_init().

Implementation of MEM_PHYS_OFFLINE Memory Notifier:
* Execute __remove_pages() exclusively for the memory block (applicable
   where a self-contained memory map was possible before).
* Shift the memory block to an inaccessible/offline state using the sclp
   unassign command.

Additional Implementation Considerations:
* When MHP_MEMMAP_ON_MEMORY is disabled, the system retains the old
   behavior. This means the memory map is allocated from default memory,
   and struct vmemmap pages are populated during the standby memory
   detection phase.
* With MHP_MEMMAP_ON_MEMORY enabled (allowing self-contained memory
   map), the memory map is allocated using the self-contained memory map
   range. Struct vmemmap pages are populated during the memory hotplug
   automatically disabled. This ensures that vmemmap pagetables do not
   consume additional memory from the default memory allocator.
* The MEM_GOING_ONLINE notifier has been modified to perform no
   operation, as MEM_PHYS_ONLINE already executes the sclp assign
* The MEM_CANCEL_ONLINE notifier now performs no operation, as
   MEM_PHYS_OFFLINE already executes the sclp unassign command.
* The call to __add_pages() in arch_add_memory() with altmap support is
   skipped. This operation is deferred and will be performed later in the
   MEM_PHYS_ONLINE notifier.

Reviewed-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Signed-off-by: Sumanth Korikkar <sumanthk@xxxxxxxxxxxxx>
  arch/s390/mm/init.c          | 16 +++++++++++++++-
  drivers/s390/char/sclp_cmd.c | 33 ++++++++++++++++++++++++++++++---
  2 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 8d9a60ccb777..db505ed590b2 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -288,6 +288,12 @@ int arch_add_memory(int nid, u64 start, u64 size,
  	rc = vmem_add_mapping(start, size);
  	if (rc)
  		return rc;
+	/*
+	 * If MHP_MEMMAP_ON_MEMORY is enabled, perform __add_pages() during memory
+	 * onlining phase
+	 */
+	if (params->altmap)
+		return 0;

So we'd have added memory blocks without a memmap? Sorry, but this seems to further hack into the s390x direction.

Maybe s390x should just provide a dedicate interface to add these memory blocks instead of adding them during boot and then relying on the old way of using online/offline set them online/offline.


David / dhildenb

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Kernel Development]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Info]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Linux Media]     [Device Mapper]

  Powered by Linux