Re: [RFC PATCH v1 4/4] mm, memory_hotplug: fix inconsistent num_poisoned_pages on memory hotremove

[Naoya Horiguchi <naoya.horiguchi@linux.dev>]

On Thu, Apr 28, 2022 at 03:16:01PM +0800, Miaohe Lin wrote:
> On 2022/4/28 12:05, HORIGUCHI NAOYA(堀口 直也) wrote:
> > On Thu, Apr 28, 2022 at 11:20:16AM +0800, Miaohe Lin wrote:
> >> On 2022/4/27 12:28, Naoya Horiguchi wrote:
> >>> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> >>>
> >>> When offlining memory section with hwpoisoned pages, the hwpoisons are
> >>> canceled. But num_poisoned_pages is not updated for that event, so the
> >>> counter becomes inconsistent.
> >>
> >> IIUC, this work is already done via clear_hwpoisoned_pages when __remove_pages.
> >> Or am I miss something?
> > 
> > Actually I had the same question when writing this patch, and found that
> > __remove_pages() seems to be called from device memory or HMM, but not from
> 
> It seems remove_memory (which calls __remove_pages) will be called as .detach callback of
> memory_device_handler in drivers/acpi/acpi_memhotplug.c. So the hwpoison info will also be
> clear for that memory ?

Sorry, you're right.  That code path also calls __remove_pages() and
clear_hwpoisoned_pages(). So most major usecases of memory hotremove seems
not to be affected by the reported problem.

Thanks,
Naoya Horiguchi