Commit d6cbd2c3 authored Mar 27, 2015 by Vitaly Kuznetsov Committed by Greg Kroah-Hartman Apr 03, 2015

Drivers: hv: hv_balloon: do not online pages in offline blocks



Currently we add memory in 128Mb blocks but the request from host can be
aligned differently. In such case we add a partially backed block and
when this block goes online we skip onlining pages which are not backed
(hv_online_page() callback serves this purpose). When we receive next
request for the same host add region we online pages which were not backed
before with hv_bring_pgs_online(). However, we don't check if the the block
in question was onlined and online this tail unconditionally. This is bad as
we avoid all online_pages() logic: these pages are not accounted, we don't
send notifications (and hv_balloon is not the only receiver of them),...
And, first of all, nobody asked as to online these pages. Solve the issue by
checking if the last previously backed page was onlined and onlining the tail
only in case it was.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent aadc3780

drivers/hv/hv_balloon.c

+11 −1

Original line number	Original line	Diff line number	Diff line
	@@ -778,7 +778,17 @@ static unsigned long handle_pg_range(unsigned long pg_start,
	pgs_ol = has->ha_end_pfn - start_pfn;		pgs_ol = has->ha_end_pfn - start_pfn;
	if (pgs_ol > pfn_cnt)		if (pgs_ol > pfn_cnt)
	pgs_ol = pfn_cnt;		pgs_ol = pfn_cnt;

			/*
			* Check if the corresponding memory block is already
			* online by checking its last previously backed page.
			* In case it is we need to bring rest (which was not
			* backed previously) online too.
			*/
			if (start_pfn > has->start_pfn &&
			!PageReserved(pfn_to_page(start_pfn - 1)))
	hv_bring_pgs_online(start_pfn, pgs_ol);		hv_bring_pgs_online(start_pfn, pgs_ol);

	has->covered_end_pfn += pgs_ol;		has->covered_end_pfn += pgs_ol;
	pfn_cnt -= pgs_ol;		pfn_cnt -= pgs_ol;
	}		}

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