From: Juergen Gross <jgross@suse.com>
To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Cc: "Juergen Gross" <jgross@suse.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
stable@vger.kernel.org,
"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
Subject: [PATCH] xen/balloon: fix cancelled balloon action
Date: Tue, 5 Oct 2021 15:34:33 +0200 [thread overview]
Message-ID: <20211005133433.32008-1-jgross@suse.com> (raw)
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 <marmarek@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/balloon.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
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,
--
2.26.2
next reply other threads:[~2021-10-05 13:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 13:34 Juergen Gross [this message]
2021-10-06 1:11 ` [PATCH] xen/balloon: fix cancelled balloon action Boris Ostrovsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211005133433.32008-1-jgross@suse.com \
--to=jgross@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=linux-kernel@vger.kernel.org \
--cc=marmarek@invisiblethingslab.com \
--cc=sstabellini@kernel.org \
--cc=stable@vger.kernel.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).