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| author | Juergen Gross <jgross@suse.com> | 2019-06-19 11:00:56 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-26 09:14:18 +0200 |
| commit | e73db096691e5f2720049502a3794a2a0c6d1b1f (patch) | |
| tree | 16652072997558f7330e9eb6ac3887ff425828bb | |
| parent | ff54c44f103825a426e46d08b5d3d76e44791a87 (diff) | |
| download | linux-stable-e73db096691e5f2720049502a3794a2a0c6d1b1f.tar.gz linux-stable-e73db096691e5f2720049502a3794a2a0c6d1b1f.tar.bz2 linux-stable-e73db096691e5f2720049502a3794a2a0c6d1b1f.zip | |
xen: let alloc_xenballooned_pages() fail if not enough memory free
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>
| -rw-r--r-- | drivers/xen/balloon.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 7ab6caef599c..d4e8b717ce2b 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -527,8 +527,15 @@ 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); @@ -567,6 +574,9 @@ 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; @@ -696,7 +706,7 @@ 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); |