From 29d11cfd8698038b87458ba4d1329b9da81150a5 Mon Sep 17 00:00:00 2001
From: Wengang Wang <wen.gang.wang@oracle.com>
Date: Tue, 18 Jul 2017 09:40:35 +0200
Subject: [PATCH] xen/grant-table: log the lack of grants
log a message when we enter this situation:
1) we already allocated the max number of available grants from hypervisor
and
2) we still need more (but the request fails because of 1)).
Sometimes the lack of grants causes IO hangs in xen_blkfront devices.
Adding this log would help debuging.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/grant-table.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index d6786b87e13b2..2c6a9114d332c 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -42,6 +42,7 @@
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/workqueue.h>
+#include <linux/ratelimit.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
@@ -1072,8 +1073,14 @@ static int gnttab_expand(unsigned int req_entries)
cur = nr_grant_frames;
extra = ((req_entries + (grefs_per_grant_frame-1)) /
grefs_per_grant_frame);
- if (cur + extra > gnttab_max_grant_frames())
+ if (cur + extra > gnttab_max_grant_frames()) {
+ pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
+ " cur=%u extra=%u limit=%u"
+ " gnttab_free_count=%u req_entries=%u\n",
+ cur, extra, gnttab_max_grant_frames(),
+ gnttab_free_count, req_entries);
return -ENOSPC;
+ }
rc = gnttab_map(cur, cur + extra - 1);
if (rc == 0)
--
GitLab