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Fri, 04 Sep 2026 13:03:39 -0700 (PDT) Received: from serhat-ubuntu.home ([212.253.216.238]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-485885c5bbdsm7868460f8f.36.2026.09.04.13.03.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Sep 2026 13:03:38 -0700 (PDT) From: Serhat Kumral To: Bart Van Assche , Jason Gunthorpe , Leon Romanovsky Cc: Sagi Grimberg , linux-rdma@vger.kernel.org, target-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Serhat Kumral Subject: [PATCH v2] RDMA/srpt: Clamp the CQ size request to max_cqe Date: Fri, 4 Sep 2026 23:02:40 +0300 Message-ID: <20260904200240.48976-1-serhatkumral1@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit srpt_create_ch_ib() asks ib_cq_pool_get() for ch->rq_size + sq_size completion queue entries. rq_size is bounded by max_qp_wr, but sq_size comes from the per-port srp_sq_size configfs attribute, which is only validated against MAX_SRPT_SRQ_SIZE (65535) and never compared with dev->attrs.max_cqe. The largest configuration srpt accepts therefore asks for 128 + 65535 = 65663 entries, while rxe caps max_cqe at 32767 and cxgb4 and ionic are in the same range. Such a request cannot be met, and ib_cq_pool_get() does not reject it. It clamps every CQ it creates to max_cqe, so no CQ it adds to the pool can ever fit the request, and it keeps allocating batches until the allocation fails. A single SRP login against such a target exhausts memory: Out of memory and no killable processes... Kernel panic - not syncing: System is deadlocked on memory Workqueue: ib_cm cm_work_handler Call Trace: __vmalloc_node_range_noprof vmalloc_user_noprof rxe_queue_init rxe_cq_from_init rxe_create_cq __ib_alloc_cq ib_cq_pool_get srpt_cm_req_recv.cold Before commit c804af2c1d31 ("IB/srpt: use new shared CQ mechanism") the same request went to ib_alloc_cq_any(), which rejected it with -EINVAL. The existing backoff, which halves sq_size when queue pair creation fails, only runs after ib_cq_pool_get() has returned, so shrink sq_size before asking for the CQ. rq_size never exceeds MAX_SRPT_RQ_SIZE (128), far below the max_cqe any device reports in practice, so the subtraction does not underflow. With the clamp the same login proceeds exactly like a correctly sized target. Fixes: c804af2c1d31 ("IB/srpt: use new shared CQ mechanism") Signed-off-by: Serhat Kumral --- Changes since v1: - Move the fix from the RDMA core to ib_srpt, as requested by Leon Romanovsky. - Clamp sq_size before the CQ request instead of rejecting oversized requests in ib_cq_pool_get(). v1: https://lore.kernel.org/linux-rdma/20260831171354.72140-1-serhatkumral1@gmail.com/ drivers/infiniband/ulp/srpt/ib_srpt.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c index 7197d95f2216..58064a4c606b 100644 --- a/drivers/infiniband/ulp/srpt/ib_srpt.c +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c @@ -1867,6 +1867,13 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch) if (!qp_init) goto out; + /* The send and receive queues share a single CQ. */ + if (ch->rq_size + sq_size > attrs->max_cqe) { + sq_size = attrs->max_cqe - ch->rq_size; + pr_debug("reduced sq_size to %u because max_cqe is %u\n", + sq_size, attrs->max_cqe); + } + retry: ch->cq = ib_cq_pool_get(sdev->device, ch->rq_size + sq_size, -1, IB_POLL_WORKQUEUE); base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 -- 2.53.0