[PATCH v2] [SCSI] scsi_dh_rdac: avoid possible deadlock in queue_mode_select

[PATCH v2] [SCSI] scsi_dh_rdac: avoid possible deadlock in queue_mode_select

[Mike Snitzer]

From: Babu Moger <babu.moger@lsi.com>

Use GFP_NOIO when allocating memory during activation of a new path to
avoid possiblility of triggering recursive writeback to a failed path.

A failed IO could cause the path to go down, then we would call
queue_mode_select() to active a new path.  Allocating memory using
GFP_KERNEL is bad to use here because completing the allocation may
require the system to write out pages to the same disk that just had
the failed path.

Signed-off-by: Babu Moger <babu.moger@lsi.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/scsi/device_handler/scsi_dh_rdac.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

v2: just refreshed and tweaked the patch header
    - v1 is available here: https://patchwork.kernel.org/patch/71073/

diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 5be3ae1..566effd 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -625,7 +625,7 @@ static int queue_mode_select(struct scsi_device *sdev,
 	struct rdac_queue_data *qdata;
 	struct rdac_controller *ctlr;
 
-	qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
+	qdata = kzalloc(sizeof(*qdata), GFP_NOIO);
 	if (!qdata)
 		return SCSI_DH_RETRY;