This is a note to let you know that I've just added the patch titled IB/iser: Fix connection teardown race condition 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: ib-iser-fix-connection-teardown-race-condition.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 <stable@xxxxxxxxxxxxxxx> know about it. >From c8c16d3bae967f1c7af541e8d016e5c51e4f010a Mon Sep 17 00:00:00 2001 From: Vladimir Neyelov <vladimirn@xxxxxxxxxxxx> Date: Sun, 21 May 2017 19:17:31 +0300 Subject: IB/iser: Fix connection teardown race condition From: Vladimir Neyelov <vladimirn@xxxxxxxxxxxx> commit c8c16d3bae967f1c7af541e8d016e5c51e4f010a upstream. Under heavy iser target(scst) start/stop stress during login/logout on iser intitiator side happened trace call provided below. The function iscsi_iser_slave_alloc iser_conn pointer could be NULL, due to the fact that function iscsi_iser_conn_stop can be called before and free iser connection. Let's protect that flow by introducing global mutex. BUG: unable to handle kernel paging request at 0000000000001018 IP: [<ffffffffc0426f7e>] iscsi_iser_slave_alloc+0x1e/0x50 [ib_iser] Call Trace: ? scsi_alloc_sdev+0x242/0x300 scsi_probe_and_add_lun+0x9e1/0xea0 ? kfree_const+0x21/0x30 ? kobject_set_name_vargs+0x76/0x90 ? __pm_runtime_resume+0x5b/0x70 __scsi_scan_target+0xf6/0x250 scsi_scan_target+0xea/0x100 iscsi_user_scan_session.part.13+0x101/0x130 [scsi_transport_iscsi] ? iscsi_user_scan_session.part.13+0x130/0x130 [scsi_transport_iscsi] iscsi_user_scan_session+0x1e/0x30 [scsi_transport_iscsi] device_for_each_child+0x50/0x90 iscsi_user_scan+0x44/0x60 [scsi_transport_iscsi] store_scan+0xa8/0x100 ? common_file_perm+0x5d/0x1c0 dev_attr_store+0x18/0x30 sysfs_kf_write+0x37/0x40 kernfs_fop_write+0x12c/0x1c0 __vfs_write+0x18/0x40 vfs_write+0xb5/0x1a0 SyS_write+0x55/0xc0 Fixes: 318d311e8f01 ("iser: Accept arbitrary sg lists mapping if the device supports it") Signed-off-by: Vladimir Neyelov <vladimirn@xxxxxxxxxxxx> Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx> Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxx> Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/infiniband/ulp/iser/iscsi_iser.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/drivers/infiniband/ulp/iser/iscsi_iser.c +++ b/drivers/infiniband/ulp/iser/iscsi_iser.c @@ -83,6 +83,7 @@ static struct scsi_host_template iscsi_i static struct iscsi_transport iscsi_iser_transport; static struct scsi_transport_template *iscsi_iser_scsi_transport; static struct workqueue_struct *release_wq; +static DEFINE_MUTEX(unbind_iser_conn_mutex); struct iser_global ig; int iser_debug_level = 0; @@ -550,12 +551,14 @@ iscsi_iser_conn_stop(struct iscsi_cls_co */ if (iser_conn) { mutex_lock(&iser_conn->state_mutex); + mutex_lock(&unbind_iser_conn_mutex); iser_conn_terminate(iser_conn); iscsi_conn_stop(cls_conn, flag); /* unbind */ iser_conn->iscsi_conn = NULL; conn->dd_data = NULL; + mutex_unlock(&unbind_iser_conn_mutex); complete(&iser_conn->stop_completion); mutex_unlock(&iser_conn->state_mutex); @@ -973,13 +976,21 @@ static int iscsi_iser_slave_alloc(struct struct iser_conn *iser_conn; struct ib_device *ib_dev; + mutex_lock(&unbind_iser_conn_mutex); + session = starget_to_session(scsi_target(sdev))->dd_data; iser_conn = session->leadconn->dd_data; + if (!iser_conn) { + mutex_unlock(&unbind_iser_conn_mutex); + return -ENOTCONN; + } ib_dev = iser_conn->ib_conn.device->ib_device; if (!(ib_dev->attrs.device_cap_flags & IB_DEVICE_SG_GAPS_REG)) blk_queue_virt_boundary(sdev->request_queue, ~MASK_4K); + mutex_unlock(&unbind_iser_conn_mutex); + return 0; } Patches currently in stable-queue which might be from vladimirn@xxxxxxxxxxxx are queue-4.9/ib-iser-fix-connection-teardown-race-condition.patch