From 764907293edc1af7ac857389af9dc858944f53dc Mon Sep 17 00:00:00 2001
From: Brian King <brking@linux.vnet.ibm.com>
Date: Tue, 12 Jan 2021 09:06:38 -0600
Subject: [PATCH] scsi: ibmvfc: Set default timeout to avoid crash during
migration
References: bsc#1181425 ltc#188252
Patch-mainline: v5.11-rc5
Git-commit: 764907293edc1af7ac857389af9dc858944f53dc
While testing live partition mobility, we have observed occasional crashes
of the Linux partition. What we've seen is that during the live migration,
for specific configurations with large amounts of memory, slow network
links, and workloads that are changing memory a lot, the partition can end
up being suspended for 30 seconds or longer. This resulted in the following
scenario:
CPU 0 CPU 1
------------------------------- ----------------------------------
scsi_queue_rq migration_store
-> blk_mq_start_request -> rtas_ibm_suspend_me
-> blk_add_timer -> on_each_cpu(rtas_percpu_suspend_me
_______________________________________V
|
V
-> IPI from CPU 1
-> rtas_percpu_suspend_me
-> __rtas_suspend_last_cpu
-- Linux partition suspended for > 30 seconds --
-> for_each_online_cpu(cpu)
plpar_hcall_norets(H_PROD
-> scsi_dispatch_cmd
-> scsi_times_out
-> scsi_abort_command
-> queue_delayed_work
-> ibmvfc_queuecommand_lck
-> ibmvfc_send_event
-> ibmvfc_send_crq
- returns H_CLOSED
<- returns SCSI_MLQUEUE_HOST_BUSY
-> __blk_mq_requeue_request
-> scmd_eh_abort_handler
-> scsi_try_to_abort_cmd
- returns SUCCESS
-> scsi_queue_insert
Normally, the SCMD_STATE_COMPLETE bit would protect against the command
completion and the timeout, but that doesn't work here, since we don't
check that at all in the SCSI_MLQUEUE_HOST_BUSY path.
In this case we end up calling scsi_queue_insert on a request that has
already been queued, or possibly even freed, and we crash.
The patch below simply increases the default I/O timeout to avoid this race
condition. This is also the timeout value that nearly all IBM SAN storage
recommends setting as the default value.
Link: https://lore.kernel.org/r/1610463998-19791-1-git-send-email-brking@linux.vnet.ibm.com
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 7312f31df878..65f168c41d23 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -3007,8 +3007,10 @@ static int ibmvfc_slave_configure(struct scsi_device *sdev)
unsigned long flags = 0;
spin_lock_irqsave(shost->host_lock, flags);
- if (sdev->type == TYPE_DISK)
+ if (sdev->type == TYPE_DISK) {
sdev->allow_restart = 1;
+ blk_queue_rq_timeout(sdev->request_queue, 120 * HZ);
+ }
spin_unlock_irqrestore(shost->host_lock, flags);
return 0;
}
--
2.26.2