From 4a39cadb740f9f43b74caaddbd39dee5a00bc103 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 22 Jul 2019 21:01:36 +0200 Subject: [PATCH] 4.9-stable patches added patches: xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch --- queue-4.9/series | 1 + ...pages-fail-if-not-enough-memory-free.patch | 70 +++++++++++++++++++ 2 files changed, 71 insertions(+) create mode 100644 queue-4.9/xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch diff --git a/queue-4.9/series b/queue-4.9/series index 3ae21c91c33..4ece05b0add 100644 --- a/queue-4.9/series +++ b/queue-4.9/series @@ -74,3 +74,4 @@ gtp-fix-illegal-context-switch-in-rcu-read-side-crit.patch gtp-fix-use-after-free-in-gtp_newlink.patch floppy-fix-div-by-zero-in-setup_format_params.patch floppy-fix-out-of-bounds-read-in-copy_buffer.patch +xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch diff --git a/queue-4.9/xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch b/queue-4.9/xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch new file mode 100644 index 00000000000..02b06cf35d9 --- /dev/null +++ b/queue-4.9/xen-let-alloc_xenballooned_pages-fail-if-not-enough-memory-free.patch @@ -0,0 +1,70 @@ +From a1078e821b605813b63bf6bca414a85f804d5c66 Mon Sep 17 00:00:00 2001 +From: Juergen Gross +Date: Wed, 19 Jun 2019 11:00:56 +0200 +Subject: xen: let alloc_xenballooned_pages() fail if not enough memory free + +From: Juergen Gross + +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 +Signed-off-by: Greg Kroah-Hartman + +--- + drivers/xen/balloon.c | 16 +++++++++++++--- + 1 file changed, 13 insertions(+), 3 deletions(-) + +--- a/drivers/xen/balloon.c ++++ b/drivers/xen/balloon.c +@@ -591,8 +591,15 @@ 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); + +@@ -631,6 +638,9 @@ 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; +@@ -754,7 +764,7 @@ 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); -- 2.47.2