From 319933a80fd4f07122466a77f93e5019d71be74c Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Tue, 5 Oct 2021 15:34:33 +0200 Subject: xen/balloon: fix cancelled balloon action MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In case a ballooning action is cancelled the new kernel thread handling the ballooning might end up in a busy loop. Fix that by handling the cancelled action gracefully. While at it introduce a short wait for the BP_WAIT case. Cc: stable@vger.kernel.org Fixes: 8480ed9c2bbd56 ("xen/balloon: use a kernel thread instead a workqueue") Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross Tested-by: Jason Andryuk Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20211005133433.32008-1-jgross@suse.com Signed-off-by: Juergen Gross --- drivers/xen/balloon.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 43ebfe36ac27..3a50f097ed3e 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -491,12 +491,12 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp) } /* - * Stop waiting if either state is not BP_EAGAIN and ballooning action is - * needed, or if the credit has changed while state is BP_EAGAIN. + * Stop waiting if either state is BP_DONE and ballooning action is + * needed, or if the credit has changed while state is not BP_DONE. */ static bool balloon_thread_cond(enum bp_state state, long credit) { - if (state != BP_EAGAIN) + if (state == BP_DONE) credit = 0; return current_credit() != credit || kthread_should_stop(); @@ -516,10 +516,19 @@ static int balloon_thread(void *unused) set_freezable(); for (;;) { - if (state == BP_EAGAIN) - timeout = balloon_stats.schedule_delay * HZ; - else + switch (state) { + case BP_DONE: + case BP_ECANCELED: timeout = 3600 * HZ; + break; + case BP_EAGAIN: + timeout = balloon_stats.schedule_delay * HZ; + break; + case BP_WAIT: + timeout = HZ; + break; + } + credit = current_credit(); wait_event_freezable_timeout(balloon_thread_wq, -- cgit v1.2.3