Re: [PATCH 2/2] mm: ksm: Support hwpoison for ksm page

[xialonglong]

在 2023/3/31 13:42, HORIGUCHI NAOYA(堀口 直也) 写道:
> On Thu, Mar 30, 2023 at 03:45:01PM +0800, Longlong Xia wrote:
> > hwpoison_user_mappings() is updated to support ksm pages, and add
> > collect_procs_ksm() to collect processes when the error hit an ksm
> > page. The difference from collect_procs_anon() is that it also needs
> > to traverse the rmap-item list on the stable node of the ksm page.
> > At the same time, add_to_kill_ksm() is added to handle ksm pages. And
> > task_in_to_kill_list() is added to avoid duplicate addition of tsk to
> > the to_kill list. This is because when scanning the list, if the pages
> > that make up the ksm page all come from the same process, they may be
> > added repeatedly.
> >
> > Signed-off-by: Longlong Xia <xialonglong1@xxxxxxxxxx>
>
> I don't find any specific issue by code review for now, so I'll try to
> test your patches.

Dear maintainer,

Can you please provide a brief update on the testing status of the patch 
and any suggestions you may have for improving it?

Thank you for your time.

Best regards,
Longlong Xia
>
> I have one comment about duplicated KSM pages.  It seems that KSM controls
> page duplication by limiting deduplication factor with max_page_sharing,
> primarily for performance reason.  But I think it's imporant from memory
> RAS's viewpoint too because that means we could allow recovery from memory
> errors on a KSM page by making affected processes to switch to the duplicated
> pages (without killing the processes!).  Maybe this might be beyond the scope
> of this patchset and I'm not sure how hard it is, but if you are interested
> in this issue, that's really nice.
>
> Thanks,
> Naoya Horiguchi