On 20.11.18 09:45, Pankaj Gupta wrote:
>
> Hi David,
>
>>
>> Mark inflated and never onlined pages PG_offline, to tell the world that
>> the content is stale and should not be dumped.
>>
>> Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
>> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
>> Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
>> Cc: Kairui Song <kasong@xxxxxxxxxx>
>> Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
>> Cc: Michal Hocko <mhocko@xxxxxxxx>
>> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
>> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>> ---
>> drivers/hv/hv_balloon.c | 14 ++++++++++++--
>> 1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
>> index 211f3fe3a038..47719862e57f 100644
>> --- a/drivers/hv/hv_balloon.c
>> +++ b/drivers/hv/hv_balloon.c
>> @@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
>> /* Check if the particular page is backed and can be onlined and online it.
>> */
>> static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
>> {
>> - if (!has_pfn_is_backed(has, page_to_pfn(pg)))
>> + if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
>> + if (!PageOffline(pg))
>> + __SetPageOffline(pg);
>> return;
>> + }
>> + if (PageOffline(pg))
>> + __ClearPageOffline(pg);
>>
>> /* This frame is currently backed; online the page. */
>> __online_page_set_limits(pg);
>> @@ -1201,6 +1206,7 @@ static void free_balloon_pages(struct hv_dynmem_device
>> *dm,
>>
>> for (i = 0; i < num_pages; i++) {
>> pg = pfn_to_page(i + start_frame);
>> + __ClearPageOffline(pg);
>
> Just thinking, do we need to care for clearing PageOffline flag before freeing
> a balloon'd page?
Yes we have to otherwise the code will crash when trying to set PageBuddy.
(only one page type at a time may be set right now, and it makes sense.
A page that is offline cannot e.g. be a buddy page)
So PageOffline is completely managed by the page owner.
>
> Thanks,
> Pankaj
--
Thanks,
David / dhildenb
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