Patch "iser-target: avoid reinitializing rdma contexts for isert commands" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

iser-target: avoid reinitializing rdma contexts for isert commands

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
iser-target-avoid-reinitializing-rdma-contexts-for-isert-commands.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bharat Potnuri <[email protected]>
Date: Tue, 28 Nov 2017 23:58:07 +0530
Subject: iser-target: avoid reinitializing rdma contexts for isert commands

From: Bharat Potnuri <[email protected]>

[ Upstream commit 66f53e6f5400578bae58db0c06d85a8820831f40 ]

isert commands that failed during isert_rdma_rw_ctx_post() are queued to Queue-Full(QF) queue and are scheduled to be reposted during queue-full queue processing. During this reposting, the rdma contexts are initialised again in isert_rdma_rw_ctx_post(), which is leaking significant memory.

unreferenced object 0xffff8830201d9640 (size 64):
comm "kworker/0:2", pid 195, jiffies 4295374851 (age 4528.436s) hex dump (first 32 bytes):

    00 60 8b cb 2e 00 00 00 00 10 00 00 00 00 00 00  .`..............
    00 90 e3 cb 2e 00 00 00 00 10 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff8170711e>] kmemleak_alloc+0x4e/0xb0
    [<ffffffff811f8ba5>] __kmalloc+0x125/0x2b0
    [<ffffffffa046b24f>] rdma_rw_ctx_init+0x15f/0x6f0 [ib_core]
    [<ffffffffa07ab644>] isert_rdma_rw_ctx_post+0xc4/0x3c0 [ib_isert]
    [<ffffffffa07ad972>] isert_put_datain+0x112/0x1c0 [ib_isert]
    [<ffffffffa07dddce>] lio_queue_data_in+0x2e/0x30 [iscsi_target_mod]
    [<ffffffffa076c322>] target_qf_do_work+0x2b2/0x4b0 [target_core_mod]
    [<ffffffff81080c3b>] process_one_work+0x1db/0x5d0
    [<ffffffff8108107d>] worker_thread+0x4d/0x3e0
    [<ffffffff81088667>] kthread+0x117/0x150
    [<ffffffff81713fa7>] ret_from_fork+0x27/0x40
    [<ffffffffffffffff>] 0xffffffffffffffff

Here is patch to use the older rdma contexts while reposting the isert commands intead of reinitialising them.

---
 drivers/infiniband/ulp/isert/ib_isert.c |    7 +++++++
 drivers/infiniband/ulp/isert/ib_isert.h |    1 +
 2 files changed, 8 insertions(+)

@@ -2098,6 +2098,9 @@ isert_rdma_rw_ctx_post(struct isert_cmd
 	u32 rkey, offset;
 	int ret;
 
+	if (cmd->ctx_init_done)
+		goto rdma_ctx_post;
+
 	if (dir == DMA_FROM_DEVICE) {
 		addr = cmd->write_va;
 		rkey = cmd->write_stag;

@@ -2125,11 +2128,15 @@ isert_rdma_rw_ctx_post(struct isert_cmd
 				se_cmd->t_data_sg, se_cmd->t_data_nents,
 				offset, addr, rkey, dir);
 	}
+
 	if (ret < 0) {
 		isert_err("Cmd: %p failed to prepare RDMA res\n", cmd);
 		return ret;
 	}
 
+	cmd->ctx_init_done = true;
+
+rdma_ctx_post:
 	ret = rdma_rw_ctx_post(&cmd->rw, conn->qp, port_num, cqe, chain_wr);
 	if (ret < 0)
 		isert_err("Cmd: %p failed to post RDMA res\n", cmd);

@@ -124,6 +124,7 @@ struct isert_cmd {
 	struct rdma_rw_ctx	rw;
 	struct work_struct	comp_work;
 	struct scatterlist	sg;
+	bool			ctx_init_done;
 };
 
 static inline struct isert_cmd *tx_desc_to_cmd(struct iser_tx_desc *desc)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/iser-target-avoid-reinitializing-rdma-contexts-for-isert-commands.patch