On Thu, Sep 10, 2020 at 01:35:32PM +0200, Laurent Dufour wrote:
That points has been raised by David, quoting him here:
IIRC, ACPI can hotadd memory while SCHEDULING, this patch would break that.
Ccing Oscar, I think he mentioned recently that this is the case with ACPI.
Oscar told that he need to investigate further on that.
I think my reply got lost.
We can see acpi hotplugs during SYSTEM_SCHEDULING:
$QEMU -enable-kvm -machine pc -smp 4,sockets=4,cores=1,threads=1 -cpu host -monitor pty \
-m size=$MEM,slots=255,maxmem=4294967296k \
-numa node,nodeid=0,cpus=0-3,mem=512 -numa node,nodeid=1,mem=512 \
-object memory-backend-ram,id=memdimm0,size=134217728 -device pc-dimm,node=0,memdev=memdimm0,id=dimm0,slot=0 \
-object memory-backend-ram,id=memdimm1,size=134217728 -device pc-dimm,node=0,memdev=memdimm1,id=dimm1,slot=1 \
-object memory-backend-ram,id=memdimm2,size=134217728 -device pc-dimm,node=0,memdev=memdimm2,id=dimm2,slot=2 \
-object memory-backend-ram,id=memdimm3,size=134217728 -device pc-dimm,node=0,memdev=memdimm3,id=dimm3,slot=3 \
-object memory-backend-ram,id=memdimm4,size=134217728 -device pc-dimm,node=1,memdev=memdimm4,id=dimm4,slot=4 \
-object memory-backend-ram,id=memdimm5,size=134217728 -device pc-dimm,node=1,memdev=memdimm5,id=dimm5,slot=5 \
-object memory-backend-ram,id=memdimm6,size=134217728 -device pc-dimm,node=1,memdev=memdimm6,id=dimm6,slot=6 \
kernel: [ 0.753643] __add_memory: nid: 0 start: 0100000000 - 0108000000 (size: 134217728)
kernel: [ 0.756950] register_mem_sect_under_node: system_state= 1
kernel: [ 0.760811] register_mem_sect_under_node+0x4f/0x230
kernel: [ 0.760811] walk_memory_blocks+0x80/0xc0
kernel: [ 0.760811] link_mem_sections+0x32/0x40
kernel: [ 0.760811] add_memory_resource+0x148/0x250
kernel: [ 0.760811] __add_memory+0x5b/0x90
kernel: [ 0.760811] acpi_memory_device_add+0x130/0x300
kernel: [ 0.760811] acpi_bus_attach+0x13c/0x1c0
kernel: [ 0.760811] acpi_bus_attach+0x60/0x1c0
kernel: [ 0.760811] acpi_bus_scan+0x33/0x70
kernel: [ 0.760811] acpi_scan_init+0xea/0x21b
kernel: [ 0.760811] acpi_init+0x2f1/0x33c
kernel: [ 0.760811] do_one_initcall+0x46/0x1f4
