3.16.75-rc1 review patch. If anyone has any objections, please let me know.
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From: Zhu Yanjun yanjun.zhu@oracle.com
commit 85cb928787eab6a2f4ca9d2a798b6f3bed53ced1 upstream.
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: Ben Hutchings ben@decadent.org.uk --- 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 @@ -663,12 +663,14 @@ static int rds_ib_flush_mr_pool(struct r 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);
}