Commit 29d11cfd authored by Wengang Wang's avatar Wengang Wang Committed by Juergen Gross
Browse files

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
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: default avatarWengang Wang <>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <>
Reviewed-by: default avatarJunxiao Bi <>
Reviewed-by: default avatarJuergen Gross <>
Signed-off-by: default avatarJuergen Gross <>
parent 0e4d394f
......@@ -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)) /
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)
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