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>

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 1377f85..933efce 100644 (file)
--- 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)) {

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index acd8251..d75b02f 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -783,6 +783,7 @@ enum ib_qp_create_flags {
        IB_QP_CREATE_BLOCK_MULTICAST_LOOPBACK   = 1 << 1,
        IB_QP_CREATE_NETIF_QP                   = 1 << 5,
        IB_QP_CREATE_SIGNATURE_EN               = 1 << 6,
+       IB_QP_CREATE_USE_GFP_NOIO               = 1 << 7,
        /* reserve bits 26-31 for low level drivers' internal use */
        IB_QP_CREATE_RESERVED_START             = 1 << 26,
        IB_QP_CREATE_RESERVED_END               = 1 << 31,