On Mon 19-02-18 14:11:03, Masayoshi Mizuma wrote:
> Hello Michal,
>
> Mon, 19 Feb 2018 18:19:16 +0100 Michal Hocko wrote:
> > On Mon 19-02-18 12:06:14, Masayoshi Mizuma wrote:
> >> From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
> >>
> >> struct page is inizialized as zero in __init_single_page().
> >> If the page is offlined page, PG_reserved flag is set in early boot
> >> time before __init_single_page(), so we should not clear the flag.
> >>
> >> The real problem is that we can not online the offlined page
> >> through following sysfs operation because offlined page is
> >> expected PG_reserved flag is set.
> >> It is not needed the initialization, so remove it simply.
> >>
> >> Code:
> >>
> >> static int online_pages_range(unsigned long start_pfn,
> >> ...
> >> if (PageReserved(pfn_to_page(start_pfn))) <= HERE!!
> >> for (i = 0; i < nr_pages; i++) {
> >> page = pfn_to_page(start_pfn + i);
> >> (*online_page_callback)(page);
> >> onlined_pages++;
> >> sysfs operation:
> >>
> >> # echo online > /sys/devices/system/node/node2/memory12288/online
> >> # cat /sys/devices/system/node/node2/memory12288/online
> >> 1
> >> # cat /sys/devices/system/node/node2/meminfo
> >> Node 2 MemTotal: 0 kB
> >
> > Nack. The patch is simply wrong. We do need to zero page for the boot
> > pages. I believe the fix you are looking for is 9bb5a391f9a5 ("mm,
> > memory_hotplug: fix memmap initialization"). Or do you still see a
> > problem with this patch applied?
>
> I have confirmed the problem is fixed by your patch 9bb5a391f9a5.
> (I had tested it in 4.15.2, so I did not notice your patch, sorry)
I have posted the backport for the 4.15 stable tree just an hour ago so
it should appear in the next stable release.
Thanks for double checking.
--
Michal Hocko
SUSE Labs
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