+++ /dev/null
-From a1078e821b605813b63bf6bca414a85f804d5c66 Mon Sep 17 00:00:00 2001
-From: Juergen Gross <jgross@suse.com>
-Date: Wed, 19 Jun 2019 11:00:56 +0200
-Subject: xen: let alloc_xenballooned_pages() fail if not enough memory free
-
-From: Juergen Gross <jgross@suse.com>
-
-commit a1078e821b605813b63bf6bca414a85f804d5c66 upstream.
-
-Instead of trying to allocate pages with GFP_USER in
-add_ballooned_pages() check the available free memory via
-si_mem_available(). GFP_USER is far less limiting memory exhaustion
-than the test via si_mem_available().
-
-This will avoid dom0 running out of memory due to excessive foreign
-page mappings especially on ARM and on x86 in PVH mode, as those don't
-have a pre-ballooned area which can be used for foreign mappings.
-
-As the normal ballooning suffers from the same problem don't balloon
-down more than si_mem_available() pages in one iteration. At the same
-time limit the default maximum number of retries.
-
-This is part of XSA-300.
-
-Signed-off-by: Juergen Gross <jgross@suse.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- drivers/xen/balloon.c | 16 +++++++++++++---
- 1 file changed, 13 insertions(+), 3 deletions(-)
-
---- a/drivers/xen/balloon.c
-+++ b/drivers/xen/balloon.c
-@@ -583,8 +583,15 @@ static void balloon_process(struct work_
- state = reserve_additional_memory();
- }
-
-- if (credit < 0)
-- state = decrease_reservation(-credit, GFP_BALLOON);
-+ if (credit < 0) {
-+ long n_pages;
-+
-+ n_pages = min(-credit, si_mem_available());
-+ state = decrease_reservation(n_pages, GFP_BALLOON);
-+ if (state == BP_DONE && n_pages != -credit &&
-+ n_pages < totalreserve_pages)
-+ state = BP_EAGAIN;
-+ }
-
- state = update_schedule(state);
-
-@@ -623,6 +630,9 @@ static int add_ballooned_pages(int nr_pa
- }
- }
-
-+ if (si_mem_available() < nr_pages)
-+ return -ENOMEM;
-+
- st = decrease_reservation(nr_pages, GFP_USER);
- if (st != BP_DONE)
- return -ENOMEM;
-@@ -746,7 +756,7 @@ static int __init balloon_init(void)
- balloon_stats.schedule_delay = 1;
- balloon_stats.max_schedule_delay = 32;
- balloon_stats.retry_count = 1;
-- balloon_stats.max_retry_count = RETRY_UNLIMITED;
-+ balloon_stats.max_retry_count = 4;
-
- #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
- set_online_page_callback(&xen_online_page);