When the following tests last for several hours, the problem will occur.
Server:
rds-stress -r 1.1.1.16 -D 1M
Client:
rds-stress -r 1.1.1.14 -s 1.1.1.16 -D 1M -T 30
The following will occur.
"
Starting up....
tsks tx/s rx/s tx+rx K/s mbi K/s mbo K/s tx us/c rtt us cpu
%
1 0 0 0.00 0.00 0.00 0.00 0.00 -1.00
1 0 0 0.00 0.00 0.00 0.00 0.00 -1.00
1 0 0 0.00 0.00 0.00 0.00 0.00 -1.00
1 0 0 0.00 0.00 0.00 0.00 0.00 -1.00
"
>From vmcore, we can find that clean_list is NULL.
>From the source code, rds_mr_flushd calls rds_ib_mr_pool_flush_worker.
Then rds_ib_mr_pool_flush_worker calls
"
rds_ib_flush_mr_pool(pool, 0, NULL);
"
Then in function
"
int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
int free_all, struct rds_ib_mr **ibmr_ret)
"
ibmr_ret is NULL.
In the source code,
"
...
list_to_llist_nodes(pool, &unmap_list, &clean_nodes, &clean_tail);
if (ibmr_ret)
*ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);
/* more than one entry in llist nodes */
if (clean_nodes->next)
llist_add_batch(clean_nodes->next, clean_tail, &pool->clean_list);
...
"
When ibmr_ret is NULL, llist_entry is not executed. clean_nodes->next
instead of clean_nodes is added in clean_list.
So clean_nodes is discarded. It can not be used again.
The workqueue is executed periodically. So more and more clean_nodes are
discarded. Finally the clean_list is NULL.
Then this problem will occur.
Fixes: 1bc144b62524 ("net, rds, Replace xlist in net/rds/xlist.h with llist")
Signed-off-by: Zhu Yanjun <yanjun.zhu@xxxxxxxxxx>
---
net/rds/ib_rdma.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index d664e9a..0b347f4 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -428,12 +428,14 @@ int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
wait_clean_list_grace();
list_to_llist_nodes(pool, &unmap_list, &clean_nodes, &clean_tail);
- if (ibmr_ret)
+ if (ibmr_ret) {
*ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);
-
+ clean_nodes = clean_nodes->next;
+ }
/* more than one entry in llist nodes */
- if (clean_nodes->next)
- llist_add_batch(clean_nodes->next, clean_tail, &pool->clean_list);
+ if (clean_nodes)
+ llist_add_batch(clean_nodes, clean_tail,
+ &pool->clean_list);
}
--
2.7.4
