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Subject[PATCH 5.1 07/70] net: rds: fix memory leak in rds_ib_flush_mr_pool
Date
From: Zhu Yanjun <yanjun.zhu@oracle.com>

[ Upstream commit 85cb928787eab6a2f4ca9d2a798b6f3bed53ced1 ]

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@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/rds/ib_rdma.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

--- 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_m
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);

}


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