Re: [PATCH v6 00/12] mm: Sub-section memory hotplug support

[Pavel Tatashin]

Hi Dan,

How do you test these patches? Do you have any instructions?

I see for example that check_hotplug_memory_range() still enforces
memory_block_size_bytes() alignment.

Also, after removing check_hotplug_memory_range(), I tried to online
16M aligned DAX memory, and got the following panic:

# echo online > /sys/devices/system/memory/memory7/state
[  202.193132] WARNING: CPU: 2 PID: 351 at drivers/base/memory.c:207
memory_block_action+0x110/0x178
[  202.193391] Modules linked in:
[  202.193698] CPU: 2 PID: 351 Comm: sh Not tainted
5.1.0-rc7_pt_devdax-00038-g865af4385544-dirty #9
[  202.193909] Hardware name: linux,dummy-virt (DT)
[  202.194122] pstate: 60000005 (nZCv daif -PAN -UAO)
[  202.194243] pc : memory_block_action+0x110/0x178
[  202.194404] lr : memory_block_action+0x90/0x178
[  202.194506] sp : ffff000016763ca0
[  202.194592] x29: ffff000016763ca0 x28: ffff80016fd29b80
[  202.194724] x27: 0000000000000000 x26: 0000000000000000
[  202.194838] x25: ffff000015546000 x24: 00000000001c0000
[  202.194949] x23: 0000000000000000 x22: 0000000000040000
[  202.195058] x21: 00000000001c0000 x20: 0000000000000008
[  202.195168] x19: 0000000000000007 x18: 0000000000000000
[  202.195281] x17: 0000000000000000 x16: 0000000000000000
[  202.195393] x15: 0000000000000000 x14: 0000000000000000
[  202.195505] x13: 0000000000000000 x12: 0000000000000000
[  202.195614] x11: 0000000000000000 x10: 0000000000000000
[  202.195744] x9 : 0000000000000000 x8 : 0000000180000000
[  202.195858] x7 : 0000000000000018 x6 : ffff000015541930
[  202.195966] x5 : ffff000015541930 x4 : 0000000000000001
[  202.196074] x3 : 0000000000000001 x2 : 0000000000000000
[  202.196185] x1 : 0000000000000070 x0 : 0000000000000000
[  202.196366] Call trace:
[  202.196455]  memory_block_action+0x110/0x178
[  202.196589]  memory_subsys_online+0x3c/0x80
[  202.196681]  device_online+0x6c/0x90
[  202.196761]  state_store+0x84/0x100
[  202.196841]  dev_attr_store+0x18/0x28
[  202.196927]  sysfs_kf_write+0x40/0x58
[  202.197010]  kernfs_fop_write+0xcc/0x1d8
[  202.197099]  __vfs_write+0x18/0x40
[  202.197187]  vfs_write+0xa4/0x1b0
[  202.197295]  ksys_write+0x64/0xd8
[  202.197430]  __arm64_sys_write+0x18/0x20
[  202.197521]  el0_svc_common.constprop.0+0x7c/0xe8
[  202.197621]  el0_svc_handler+0x28/0x78
[  202.197706]  el0_svc+0x8/0xc
[  202.197828] ---[ end trace 57719823dda6d21e ]---

Thank you,
Pasha