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xen/balloon: fix cancelled balloon action

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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: 8480ed9c2b ("xen/balloon: use a kernel thread instead a workqueue")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20211005133433.32008-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Juergen Gross 2021-10-05 15:34:33 +02:00
parent 9c11112c0e
commit 319933a80f
1 changed files with 15 additions and 6 deletions
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21
drivers/xen/balloon.c
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@ -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,