[PATCH 0/2] xprtrdma device removal bug fixes

[PATCH 0/2] xprtrdma device removal bug fixes

[Chuck Lever]

Hi Anna-

Here are two bug fixes related to DEVICE_REMOVAL support in the
RPC/RDMA client. Can these go in 5.5-rc ?

Both of these deserve a stable tag, IMHO, as does 572c4b40a394
("xprtrdma: Fix MR list handling") which I've already sent as
part of for-5.5.

There's one remaining crasher that I hit when removing a device
while there are active NFS mounts. I should have a fix for that
one soon.

---

Chuck Lever (2):
      xprtrdma: Fix create_qp crash on device unload
      xprtrdma: Fix completion wait during device removal


 net/sunrpc/xprtrdma/verbs.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--
Chuck Lever

[PATCH 1/2] 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 2/2] 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 @@ static void rpcrdma_update_cm_private(struct rpcrdma_xprt *r_xprt,
 			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 @@ static void rpcrdma_update_cm_private(struct rpcrdma_xprt *r_xprt,
 	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);

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

[Chuck Lever]

> On Dec 2, 2019, at 11:28 AM, Chuck Lever <chuck.lever@oracle.com> wrote:
> 
> I've found that on occasion, "rmmod <dev>" will hang while if an NFS
> is under load.

ETOOMUCHTURKEY. How about:

I've found that on occasion, "rmmod <dev>" hangs while an NFS mount
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 @@ static void rpcrdma_update_cm_private(struct rpcrdma_xprt *r_xprt,
> 			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 @@ static void rpcrdma_update_cm_private(struct rpcrdma_xprt *r_xprt,
> 	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);
> 

--
Chuck Lever