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[68.61.232.219]) by smtp.gmail.com with ESMTPSA id g190sm23629820ywf.41.2020.01.03.08.52.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Jan 2020 08:52:23 -0800 (PST) Received: from morisot.1015granger.net (morisot.1015granger.net [192.168.1.67]) by gateway.1015granger.net (8.14.7/8.14.7) with ESMTP id 003GqM4A016375; Fri, 3 Jan 2020 16:52:22 GMT Subject: [PATCH 3/3] xprtrdma: Fix oops in Receive handler after device removal From: Chuck Lever To: anna.schumaker@netapp.com Cc: linux-nfs@vger.kernel.org Date: Fri, 03 Jan 2020 11:52:22 -0500 Message-ID: <157807034285.3637.1107321602862156718.stgit@morisot.1015granger.net> In-Reply-To: <157807026361.3637.2531475820164100233.stgit@morisot.1015granger.net> References: <157807026361.3637.2531475820164100233.stgit@morisot.1015granger.net> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org 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 --- 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;