[PATCH 0/3] Fixes for v5.4

[PATCH 0/3] Fixes for v5.4

[Chuck Lever]

Hi Anna-

I haven't seen these three go into 5.4 stable yet. Can they be
pushed soon?

---

Chuck Lever (3):
      xprtrdma: Fix create_qp crash on device unload
      xprtrdma: Fix completion wait during device removal
      xprtrdma: Fix oops in Receive handler after device removal


 net/sunrpc/xprtrdma/verbs.c     |   29 ++++++++++++++++++++++-------
 net/sunrpc/xprtrdma/xprt_rdma.h |    2 ++
 2 files changed, 24 insertions(+), 7 deletions(-)

--
Chuck Lever

[PATCH 1/3] xprtrdma: Fix create_qp crash on device unload

[Chuck Lever]

On device re-insertion, the RDMA device driver crashes trying to set
up a new QP:

Nov 27 16:32:06 manet kernel: BUG: kernel NULL pointer dereference, address: 00000000000001c0
Nov 27 16:32:06 manet kernel: #PF: supervisor write access in kernel mode
Nov 27 16:32:06 manet kernel: #PF: error_code(0x0002) - not-present page
Nov 27 16:32:06 manet kernel: PGD 0 P4D 0
Nov 27 16:32:06 manet kernel: Oops: 0002 [#1] SMP
Nov 27 16:32:06 manet kernel: CPU: 1 PID: 345 Comm: kworker/u28:0 Tainted: G        W         5.4.0 #852
Nov 27 16:32:06 manet kernel: Hardware name: Supermicro SYS-6028R-T/X10DRi, BIOS 1.1a 10/16/2015
Nov 27 16:32:06 manet kernel: Workqueue: xprtiod xprt_rdma_connect_worker [rpcrdma]
Nov 27 16:32:06 manet kernel: RIP: 0010:atomic_try_cmpxchg+0x2/0x12
Nov 27 16:32:06 manet kernel: Code: ff ff 48 8b 04 24 5a c3 c6 07 00 0f 1f 40 00 c3 31 c0 48 81 ff 08 09 68 81 72 0c 31 c0 48 81 ff 83 0c 68 81 0f 92 c0 c3 8b 06 <f0> 0f b1 17 0f 94 c2 84 d2 75 02 89 06 88 d0 c3 53 ba 01 00 00 00
Nov 27 16:32:06 manet kernel: RSP: 0018:ffffc900035abbf0 EFLAGS: 00010046
Nov 27 16:32:06 manet kernel: RAX: 0000000000000000 RBX: 00000000000001c0 RCX: 0000000000000000
Nov 27 16:32:06 manet kernel: RDX: 0000000000000001 RSI: ffffc900035abbfc RDI: 00000000000001c0
Nov 27 16:32:06 manet kernel: RBP: ffffc900035abde0 R08: 000000000000000e R09: ffffffffffffc000
Nov 27 16:32:06 manet kernel: R10: 0000000000000000 R11: 000000000002e800 R12: ffff88886169d9f8
Nov 27 16:32:06 manet kernel: R13: ffff88886169d9f4 R14: 0000000000000246 R15: 0000000000000000
Nov 27 16:32:06 manet kernel: FS:  0000000000000000(0000) GS:ffff88846fa40000(0000) knlGS:0000000000000000
Nov 27 16:32:06 manet kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Nov 27 16:32:06 manet kernel: CR2: 00000000000001c0 CR3: 0000000002009006 CR4: 00000000001606e0
Nov 27 16:32:06 manet kernel: Call Trace:
Nov 27 16:32:06 manet kernel: do_raw_spin_lock+0x2f/0x5a
Nov 27 16:32:06 manet kernel: create_qp_common.isra.47+0x856/0xadf [mlx4_ib]
Nov 27 16:32:06 manet kernel: ? slab_post_alloc_hook.isra.60+0xa/0x1a
Nov 27 16:32:06 manet kernel: ? __kmalloc+0x125/0x139
Nov 27 16:32:06 manet kernel: mlx4_ib_create_qp+0x57f/0x972 [mlx4_ib]

The fix is to copy the qp_init_attr struct that was just created by
rpcrdma_ep_create() instead of using the one from the previous
connection instance.

Fixes: 98ef77d1aaa7 ("xprtrdma: Send Queue size grows after a reconnect")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 77c7dd7f05e8..3a56458e8c05 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -599,6 +599,7 @@ static int rpcrdma_ep_recreate_xprt(struct rpcrdma_xprt *r_xprt,
 				    struct ib_qp_init_attr *qp_init_attr)
 {
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+	struct rpcrdma_ep *ep = &r_xprt->rx_ep;
 	int rc, err;
 
 	trace_xprtrdma_reinsert(r_xprt);
@@ -613,6 +614,7 @@ static int rpcrdma_ep_recreate_xprt(struct rpcrdma_xprt *r_xprt,
 		pr_err("rpcrdma: rpcrdma_ep_create returned %d\n", err);
 		goto out2;
 	}
+	memcpy(qp_init_attr, &ep->rep_attr, sizeof(*qp_init_attr));
 
 	rc = -ENETUNREACH;
 	err = rdma_create_qp(ia->ri_id, ia->ri_pd, qp_init_attr);

[PATCH 2/3] xprtrdma: Fix completion wait during device removal

[Chuck Lever]

I've found that on occasion, "rmmod <dev>" will hang while if an NFS
is under load.

Ensure that ri_remove_done is initialized only just before the
transport is woken up to force a close. This avoids the completion
possibly getting initialized again while the CM event handler is
waiting for a wake-up.

Fixes: bebd031866ca ("xprtrdma: Support unplugging an HCA from under an NFS mount")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 3a56458e8c05..2c40465a19e1 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -244,6 +244,7 @@ rpcrdma_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
 			ia->ri_id->device->name,
 			rpcrdma_addrstr(r_xprt), rpcrdma_portstr(r_xprt));
 #endif
+		init_completion(&ia->ri_remove_done);
 		set_bit(RPCRDMA_IAF_REMOVING, &ia->ri_flags);
 		ep->rep_connected = -ENODEV;
 		xprt_force_disconnect(xprt);
@@ -297,7 +298,6 @@ rpcrdma_create_id(struct rpcrdma_xprt *xprt, struct rpcrdma_ia *ia)
 	int rc;
 
 	init_completion(&ia->ri_done);
-	init_completion(&ia->ri_remove_done);
 
 	id = rdma_create_id(xprt->rx_xprt.xprt_net, rpcrdma_cm_event_handler,
 			    xprt, RDMA_PS_TCP, IB_QPT_RC);

[PATCH 3/3] xprtrdma: Fix oops in Receive handler after device removal

[Chuck Lever]

Since v5.4, a device removal occasionally triggered this oops:

Dec  2 17:13:53 manet kernel: BUG: unable to handle page fault for address: 0000000c00000219
Dec  2 17:13:53 manet kernel: #PF: supervisor read access in kernel mode
Dec  2 17:13:53 manet kernel: #PF: error_code(0x0000) - not-present page
Dec  2 17:13:53 manet kernel: PGD 0 P4D 0
Dec  2 17:13:53 manet kernel: Oops: 0000 [#1] SMP
Dec  2 17:13:53 manet kernel: CPU: 2 PID: 468 Comm: kworker/2:1H Tainted: G        W         5.4.0-00050-g53717e43af61 #883
Dec  2 17:13:53 manet kernel: Hardware name: Supermicro SYS-6028R-T/X10DRi, BIOS 1.1a 10/16/2015
Dec  2 17:13:53 manet kernel: Workqueue: ib-comp-wq ib_cq_poll_work [ib_core]
Dec  2 17:13:53 manet kernel: RIP: 0010:rpcrdma_wc_receive+0x7c/0xf6 [rpcrdma]
Dec  2 17:13:53 manet kernel: Code: 6d 8b 43 14 89 c1 89 45 78 48 89 4d 40 8b 43 2c 89 45 14 8b 43 20 89 45 18 48 8b 45 20 8b 53 14 48 8b 30 48 8b 40 10 48 8b 38 <48> 8b 87 18 02 00 00 48 85 c0 75 18 48 8b 05 1e 24 c4 e1 48 85 c0
Dec  2 17:13:53 manet kernel: RSP: 0018:ffffc900035dfe00 EFLAGS: 00010246
Dec  2 17:13:53 manet kernel: RAX: ffff888467290000 RBX: ffff88846c638400 RCX: 0000000000000048
Dec  2 17:13:53 manet kernel: RDX: 0000000000000048 RSI: 00000000f942e000 RDI: 0000000c00000001
Dec  2 17:13:53 manet kernel: RBP: ffff888467611b00 R08: ffff888464e4a3c4 R09: 0000000000000000
Dec  2 17:13:53 manet kernel: R10: ffffc900035dfc88 R11: fefefefefefefeff R12: ffff888865af4428
Dec  2 17:13:53 manet kernel: R13: ffff888466023000 R14: ffff88846c63f000 R15: 0000000000000010
Dec  2 17:13:53 manet kernel: FS:  0000000000000000(0000) GS:ffff88846fa80000(0000) knlGS:0000000000000000
Dec  2 17:13:53 manet kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec  2 17:13:53 manet kernel: CR2: 0000000c00000219 CR3: 0000000002009002 CR4: 00000000001606e0
Dec  2 17:13:53 manet kernel: Call Trace:
Dec  2 17:13:53 manet kernel: __ib_process_cq+0x5c/0x14e [ib_core]
Dec  2 17:13:53 manet kernel: ib_cq_poll_work+0x26/0x70 [ib_core]
Dec  2 17:13:53 manet kernel: process_one_work+0x19d/0x2cd
Dec  2 17:13:53 manet kernel: ? cancel_delayed_work_sync+0xf/0xf
Dec  2 17:13:53 manet kernel: worker_thread+0x1a6/0x25a
Dec  2 17:13:53 manet kernel: ? cancel_delayed_work_sync+0xf/0xf
Dec  2 17:13:53 manet kernel: kthread+0xf4/0xf9
Dec  2 17:13:53 manet kernel: ? kthread_queue_delayed_work+0x74/0x74
Dec  2 17:13:53 manet kernel: ret_from_fork+0x24/0x30

The proximal cause is that this rpcrdma_rep has a rr_rdmabuf that
is still pointing to the old ib_device, which has been freed. The
only way that is possible is if this rpcrdma_rep was not destroyed
by rpcrdma_ia_remove.

Debugging showed that was indeed the case: this rpcrdma_rep was
still in use by a completing RPC at the time of the device removal,
and thus wasn't on the rep free list. So, it was not found by
rpcrdma_reps_destroy().

The fix is to introduce a list of all rpcrdma_reps so that they all
can be found when a device is removed. That list is used to perform
only regbuf DMA unmapping, replacing that call to
rpcrdma_reps_destroy().

Meanwhile, to prevent corruption of this list, I've moved the
destruction of temp rpcrdma_rep objects to rpcrdma_post_recvs().
rpcrdma_xprt_drain() ensures that post_recvs (and thus rep_destroy) is
not invoked while rpcrdma_reps_unmap is walking rb_all_reps, thus
protecting the rb_all_reps list.

Fixes: b0b227f071a0 ("xprtrdma: Use an llist to manage free rpcrdma_reps")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c     |   25 +++++++++++++++++++------
 net/sunrpc/xprtrdma/xprt_rdma.h |    2 ++
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 2c40465a19e1..fda3889993cb 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -77,7 +77,7 @@
 static void rpcrdma_sendctx_put_locked(struct rpcrdma_xprt *r_xprt,
 				       struct rpcrdma_sendctx *sc);
 static void rpcrdma_reqs_reset(struct rpcrdma_xprt *r_xprt);
-static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf);
+static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt);
 static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
 static void rpcrdma_mrs_destroy(struct rpcrdma_xprt *r_xprt);
 static struct rpcrdma_regbuf *
@@ -421,7 +421,7 @@ rpcrdma_ia_remove(struct rpcrdma_ia *ia)
 	/* The ULP is responsible for ensuring all DMA
 	 * mappings and MRs are gone.
 	 */
-	rpcrdma_reps_destroy(buf);
+	rpcrdma_reps_unmap(r_xprt);
 	list_for_each_entry(req, &buf->rb_allreqs, rl_all) {
 		rpcrdma_regbuf_dma_unmap(req->rl_rdmabuf);
 		rpcrdma_regbuf_dma_unmap(req->rl_sendbuf);
@@ -1092,6 +1092,7 @@ static struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 	rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
 	rep->rr_recv_wr.num_sge = 1;
 	rep->rr_temp = temp;
+	list_add(&rep->rr_all, &r_xprt->rx_buf.rb_all_reps);
 	return rep;
 
 out_free:
@@ -1102,6 +1103,7 @@ static struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
 
 static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
 {
+	list_del(&rep->rr_all);
 	rpcrdma_regbuf_free(rep->rr_rdmabuf);
 	kfree(rep);
 }
@@ -1120,10 +1122,16 @@ static struct rpcrdma_rep *rpcrdma_rep_get_locked(struct rpcrdma_buffer *buf)
 static void rpcrdma_rep_put(struct rpcrdma_buffer *buf,
 			    struct rpcrdma_rep *rep)
 {
-	if (!rep->rr_temp)
-		llist_add(&rep->rr_node, &buf->rb_free_reps);
-	else
-		rpcrdma_rep_destroy(rep);
+	llist_add(&rep->rr_node, &buf->rb_free_reps);
+}
+
+static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_rep *rep;
+
+	list_for_each_entry(rep, &buf->rb_all_reps, rr_all)
+		rpcrdma_regbuf_dma_unmap(rep->rr_rdmabuf);
 }
 
 static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf)
@@ -1154,6 +1162,7 @@ int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
 
 	INIT_LIST_HEAD(&buf->rb_send_bufs);
 	INIT_LIST_HEAD(&buf->rb_allreqs);
+	INIT_LIST_HEAD(&buf->rb_all_reps);
 
 	rc = -ENOMEM;
 	for (i = 0; i < buf->rb_max_requests; i++) {
@@ -1506,6 +1515,10 @@ void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
 	wr = NULL;
 	while (needed) {
 		rep = rpcrdma_rep_get_locked(buf);
+		if (rep && rep->rr_temp) {
+			rpcrdma_rep_destroy(rep);
+			continue;
+		}
 		if (!rep)
 			rep = rpcrdma_rep_create(r_xprt, temp);
 		if (!rep)
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 5d15140a0266..d796d68609ed 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -203,6 +203,7 @@ struct rpcrdma_rep {
 	struct xdr_stream	rr_stream;
 	struct llist_node	rr_node;
 	struct ib_recv_wr	rr_recv_wr;
+	struct list_head	rr_all;
 };
 
 /* To reduce the rate at which a transport invokes ib_post_recv
@@ -368,6 +369,7 @@ struct rpcrdma_buffer {
 
 	struct list_head	rb_allreqs;
 	struct list_head	rb_all_mrs;
+	struct list_head	rb_all_reps;
 
 	struct llist_head	rb_free_reps;