IB: Add a QP creation flag to use GFP_NOIO allocations

This addresses a problem where NFS client writes over IPoIB connected
mode may deadlock on memory allocation/writeback.

The problem is not directly memory reclamation.  There is an indirect
dependency between network filesystems writing back pages and
ipoib_cm_tx_init() due to how a kworker is used.  Page reclaim cannot
make forward progress until ipoib_cm_tx_init() succeeds and it is
stuck in page reclaim itself waiting for network transmission.
Ordinarily this situation may be avoided by having the caller use
GFP_NOFS but ipoib_cm_tx_init() does not have that information.

To address this, take a general approach and add a new QP creation
flag that tells the low-level hardware driver to use GFP_NOIO for the
memory allocations related to the new QP.

Use the new flag in the ipoib connected mode path, and if the driver
doesn't support it, re-issue the QP creation without the flag.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 1377f85911c2..933efcea0d03 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -1030,10 +1030,20 @@ static struct ib_qp *ipoib_cm_create_tx_qp(struct net_device *dev, struct ipoib_
                 .cap.max_send_sge       = 1,
                 .sq_sig_type            = IB_SIGNAL_ALL_WR,
                 .qp_type                = IB_QPT_RC,
-                .qp_context             = tx
+                .qp_context             = tx,
+                .create_flags           = IB_QP_CREATE_USE_GFP_NOIO
         };
 
-        return ib_create_qp(priv->pd, &attr);
+        struct ib_qp *tx_qp;
+
+        tx_qp = ib_create_qp(priv->pd, &attr);
+        if (PTR_ERR(tx_qp) == -EINVAL) {
+                ipoib_warn(priv, "can't use GFP_NOIO for QPs on device %s, using GFP_KERNEL\n",
+                           priv->ca->name);
+                attr.create_flags &= ~IB_QP_CREATE_USE_GFP_NOIO;
+                tx_qp = ib_create_qp(priv->pd, &attr);
+        }
+        return tx_qp;
 }
 
 static int ipoib_cm_send_req(struct net_device *dev,
@@ -1104,12 +1114,14 @@ static int ipoib_cm_tx_init(struct ipoib_cm_tx *p, u32 qpn,
         struct ipoib_dev_priv *priv = netdev_priv(p->dev);
         int ret;
 
-        p->tx_ring = vzalloc(ipoib_sendq_size * sizeof *p->tx_ring);
+        p->tx_ring = __vmalloc(ipoib_sendq_size * sizeof *p->tx_ring,
+                               GFP_NOIO, PAGE_KERNEL);
         if (!p->tx_ring) {
                 ipoib_warn(priv, "failed to allocate tx ring\n");
                 ret = -ENOMEM;
                 goto err_tx;
         }
+        memset(p->tx_ring, 0, ipoib_sendq_size * sizeof *p->tx_ring);
 
         p->qp = ipoib_cm_create_tx_qp(p->dev, p);
         if (IS_ERR(p->qp)) {