diff options
Diffstat (limited to 'xen-let-alloc_xenballooned_pages-fail-if-not-enough-.patch')
| -rw-r--r-- | xen-let-alloc_xenballooned_pages-fail-if-not-enough-.patch | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/xen-let-alloc_xenballooned_pages-fail-if-not-enough-.patch b/xen-let-alloc_xenballooned_pages-fail-if-not-enough-.patch new file mode 100644 index 000000000..9017a3fbe --- /dev/null +++ b/xen-let-alloc_xenballooned_pages-fail-if-not-enough-.patch @@ -0,0 +1,70 @@ +From 2bb6248308c9e2b8bfd13791c8b36fe21d230ed3 Mon Sep 17 00:00:00 2001 +From: Juergen Gross <jgross@suse.com> +Date: Wed, 19 Jun 2019 11:00:56 +0200 +Subject: [PATCH 2/2] xen: let alloc_xenballooned_pages() fail if not enough + memory free + +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> +--- + drivers/xen/balloon.c | 16 +++++++++++++--- + 1 file changed, 13 insertions(+), 3 deletions(-) + +diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c +index d37dd5bb7a8f..559768dc2567 100644 +--- a/drivers/xen/balloon.c ++++ b/drivers/xen/balloon.c +@@ -538,8 +538,15 @@ static void balloon_process(struct work_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); + +@@ -578,6 +585,9 @@ static int add_ballooned_pages(int nr_pages) + } + } + ++ if (si_mem_available() < nr_pages) ++ return -ENOMEM; ++ + st = decrease_reservation(nr_pages, GFP_USER); + if (st != BP_DONE) + return -ENOMEM; +@@ -710,7 +720,7 @@ 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); +-- +2.21.0 + |