RDSRDMA: Fix cleanup of rds_iw_mr_pool

In the rds_iw_mr_pool struct the free_pinned field keeps track of
memory pinned by free MRs. While this field is incremented properly
upon allocation, it is never decremented upon unmapping. This would
cause the rds_rdma module to crash the kernel upon unloading, by
triggering the BUG_ON in the rds_iw_destroy_mr_pool function.

This change keeps track of the MRs that become unpinned, so that
free_pinned can be decremented appropriately.

Signed-off-by: Jonathan Lallinger <jonathan@ogc.us>
Signed-off-by: Steve Wise <swise@ogc.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/rds/iw_rdma.c b/net/rds/iw_rdma.c
index 8b77edb..4e1de17 100644 (file)
--- a/net/rds/iw_rdma.c
+++ b/net/rds/iw_rdma.c
@@ -84,7 +84,8 @@ static int rds_iw_map_fastreg(struct rds_iw_mr_pool *pool,
 static void rds_iw_free_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);
 static unsigned int rds_iw_unmap_fastreg_list(struct rds_iw_mr_pool *pool,
                        struct list_head *unmap_list,
-                       struct list_head *kill_list);
+                       struct list_head *kill_list,
+                       int *unpinned);
 static void rds_iw_destroy_fastreg(struct rds_iw_mr_pool *pool, struct rds_iw_mr *ibmr);
 
 static int rds_iw_get_device(struct rds_sock *rs, struct rds_iw_device **rds_iwdev, struct rdma_cm_id **cm_id)
@@ -499,7 +500,7 @@ static int rds_iw_flush_mr_pool(struct rds_iw_mr_pool *pool, int free_all)
        LIST_HEAD(unmap_list);
        LIST_HEAD(kill_list);
        unsigned long flags;
-       unsigned int nfreed = 0, ncleaned = 0, free_goal;
+       unsigned int nfreed = 0, ncleaned = 0, unpinned = 0, free_goal;
        int ret = 0;
 
        rds_iw_stats_inc(s_iw_rdma_mr_pool_flush);
@@ -524,7 +525,8 @@ static int rds_iw_flush_mr_pool(struct rds_iw_mr_pool *pool, int free_all)
         * will be destroyed by the unmap function.
         */
        if (!list_empty(&unmap_list)) {
-               ncleaned = rds_iw_unmap_fastreg_list(pool, &unmap_list, &kill_list);
+               ncleaned = rds_iw_unmap_fastreg_list(pool, &unmap_list,
+                                                    &kill_list, &unpinned);
                /* If we've been asked to destroy all MRs, move those
                 * that were simply cleaned to the kill list */
                if (free_all)
@@ -548,6 +550,7 @@ static int rds_iw_flush_mr_pool(struct rds_iw_mr_pool *pool, int free_all)
                spin_unlock_irqrestore(&pool->list_lock, flags);
        }
 
+       atomic_sub(unpinned, &pool->free_pinned);
        atomic_sub(ncleaned, &pool->dirty_count);
        atomic_sub(nfreed, &pool->item_count);
 
@@ -828,7 +831,8 @@ static void rds_iw_free_fastreg(struct rds_iw_mr_pool *pool,
 
 static unsigned int rds_iw_unmap_fastreg_list(struct rds_iw_mr_pool *pool,
                                struct list_head *unmap_list,
-                               struct list_head *kill_list)
+                               struct list_head *kill_list,
+                               int *unpinned)
 {
        struct rds_iw_mapping *mapping, *next;
        unsigned int ncleaned = 0;
@@ -855,6 +859,7 @@ static unsigned int rds_iw_unmap_fastreg_list(struct rds_iw_mr_pool *pool,
 
                spin_lock_irqsave(&pool->list_lock, flags);
                list_for_each_entry_safe(mapping, next, unmap_list, m_list) {
+                       *unpinned += mapping->m_sg.len;
                        list_move(&mapping->m_list, &laundered);
                        ncleaned++;
                }