BMC/Intel-BMC/linux.git/drivers/virtio/virtio_balloon.c, branch dev-4.4

balloon: check the number of available pages in leak balloon

2016-08-20T16:09:23+00:00

commit 37cf99e08c6fb4dcea0f9ad2b13b6daa8c76a711 upstream. The balloon has a special mechanism that is subscribed to the oom notification which leads to deflation for a fixed number of pages. The number is always fixed even when the balloon is fully deflated. But leak_balloon did not expect that the pages to deflate will be more than taken, and raise a "BUG" in balloon_page_dequeue when page list will be empty. So, the simplest solution would be to check that the number of releases pages is less or equal to the number taken pages. Signed-off-by: Konstantin Neumoin Signed-off-by: Denis V. Lunev CC: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

virtio_balloon: fix PFN format for virtio-1

2016-07-27T16:47:34+00:00

commit 87c9403b0d1de4676b0bd273eea68fcf6de68e68 upstream. Everything should be LE when using virtio-1, but the linux balloon driver does not seem to care about that. Reported-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Tested-by: Cornelia Huck Reviewed-by: Cornelia Huck Signed-off-by: Greg Kroah-Hartman

virtio_balloon: fix race by fill and leak

2016-03-03T23:07:17+00:00

commit f68b992bbb474641881932c61c92dcfa6f5b3689 upstream. During my compaction-related stuff, I encountered a bug with ballooning. With repeated inflating and deflating cycle, guest memory( ie, cat /proc/meminfo | grep MemTotal) is decreased and couldn't be recovered. The reason is balloon_lock doesn't cover release_pages_balloon so struct virtio_balloon fields could be overwritten by race of fill_balloon(e,g, vb->*pfns could be critical). This patch fixes it in my test. Signed-off-by: Minchan Kim Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman

virtio_balloon: do not change memory amount visible via /proc/meminfo

2015-09-08T10:32:11+00:00

Balloon device is frequently used as a mean of cooperative memory control in between guest and host to manage memory overcommitment. This is the typical case for any hosting workload when KVM guest is provided for end-user. Though there is a problem in this setup. The end-user and hosting provider have signed SLA agreement in which some amount of memory is guaranted for the guest. The good thing is that this memory will be given to the guest when the guest will really need it (f.e. with OOM in guest and with VIRTIO_BALLOON_F_DEFLATE_ON_OOM configuration flag set). The bad thing is that end-user does not know this. Balloon by default reduce the amount of memory exposed to the end-user each time when the page is stolen from guest or returned back by using adjust_managed_page_count and thus /proc/meminfo shows reduced amount of memory. Fortunately the solution is simple, we should just avoid to call adjust_managed_page_count with VIRTIO_BALLOON_F_DEFLATE_ON_OOM set. Signed-off-by: Denis V. Lunev CC: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin

virtio_ballon: change stub of release_pages_by_pfn

2015-09-08T10:31:51+00:00

and rename it to release_pages_balloon. The function originally takes arrays of pfns and now it takes pointer to struct virtio_ballon. This change is necessary to conditionally call adjust_managed_page_count in the next patch. Signed-off-by: Denis V. Lunev CC: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin

virtio_balloon: transitional interface

2015-04-15T03:11:09+00:00

Virtio 1.0 doesn't include a modern balloon device. But it's not a big change to support a transitional balloon device: this has the advantage of supporting existing drivers, transparently. Signed-off-by: Michael S. Tsirkin Acked-by: Cornelia Huck Signed-off-by: Rusty Russell

virtio-balloon: do not call blocking ops when !TASK_RUNNING

2015-03-10T01:26:15+00:00

virtio balloon has this code: wait_event_interruptible(vb->config_change, (diff = towards_target(vb)) != 0 || vb->need_stats_update || kthread_should_stop() || freezing(current)); Which is a problem because towards_target() call might block after wait_event_interruptible sets task state to TAST_INTERRUPTIBLE, causing the task_struct::state collision typical of nesting of sleeping primitives See also http://lwn.net/Articles/628628/ or Thomas's bug report http://article.gmane.org/gmane.linux.kernel.virtualization/24846 for a fuller explanation. To fix, rewrite using wait_woken. Cc: stable@vger.kernel.org Reported-by: Thomas Huth Signed-off-by: Michael S. Tsirkin Tested-by: Thomas Huth Reviewed-by: Cornelia Huck Signed-off-by: Rusty Russell

virtio_balloon: set DRIVER_OK before using device

2015-03-10T01:18:28+00:00

virtio spec requires that all drivers set DRIVER_OK before using devices. While balloon isn't yet included in the virtio 1 spec, previous spec versions also required this. virtio balloon might violate this rule: probe calls kthread_run before setting DRIVER_OK, which might run immediately and cause balloon to inflate/deflate. To fix, call virtio_device_ready before running the kthread. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell Cc: stable@kernel.org

virtio_balloon: coding style fixes

2015-01-21T05:58:56+00:00

Most of our code has struct foo { } Fix two instances where balloon is inconsistent. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell

virtio/balloon: verify device has config space

2015-01-21T05:58:48+00:00

Some devices might not implement config space access (e.g. remoteproc used not to - before 3.9). virtio/balloon needs config space access so make it fail gracefully if not there. Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell