The patch below does not apply to the 5.5.y-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cc41f11a21a51d6869d71e525a7264c748d7c0d7 Mon Sep 17 00:00:00 2001

From: Sreekanth Reddy sreekanth.reddy@broadcom.com Date: Fri, 27 Mar 2020 05:52:43 -0400 Subject: [PATCH] scsi: mpt3sas: Fix kernel panic observed on soft HBA unplug

Generic protection fault type kernel panic is observed when user performs soft (ordered) HBA unplug operation while IOs are running on drives connected to HBA.

When user performs ordered HBA removal operation, the kernel calls PCI device's .remove() call back function where driver is flushing out all the outstanding SCSI IO commands with DID_NO_CONNECT host byte and also unmaps sg buffers allocated for these IO commands.

However, in the ordered HBA removal case (unlike of real HBA hot removal), HBA device is still alive and hence HBA hardware is performing the DMA operations to those buffers on the system memory which are already unmapped while flushing out the outstanding SCSI IO commands and this leads to kernel panic.

Don't flush out the outstanding IOs from .remove() path in case of ordered removal since HBA will be still alive in this case and it can complete the outstanding IOs. Flush out the outstanding IOs only in case of 'physical HBA hot unplug' where there won't be any communication with the HBA.

During shutdown also it is possible that HBA hardware can perform DMA operations on those outstanding IO buffers which are completed with DID_NO_CONNECT by the driver from .shutdown(). So same above fix is applied in shutdown path as well.

It is safe to drop the outstanding commands when HBA is inaccessible such as when permanent PCI failure happens, when HBA is in non-operational state, or when someone does a real HBA hot unplug operation. Since driver knows that HBA is inaccessible during these cases, it is safe to drop the outstanding commands instead of waiting for SCSI error recovery to kick in and clear these outstanding commands.

Link: https://lore.kernel.org/r/1585302763-23007-1-git-send-email-sreekanth.reddy@... Fixes: c666d3be99c0 ("scsi: mpt3sas: wait for and flush running commands on shutdown/unload") Cc: stable@vger.kernel.org #v4.14.174+ Signed-off-by: Sreekanth Reddy sreekanth.reddy@broadcom.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com

diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c b/drivers/scsi/mpt3sas/mpt3sas_scsih.c index 778d5e6ce385..04a40afe60e3 100644 --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c @@ -9908,8 +9908,8 @@ static void scsih_remove(struct pci_dev *pdev)

ioc->remove_host = 1;

- mpt3sas_wait_for_commands_to_complete(ioc); - _scsih_flush_running_cmds(ioc); + if (!pci_device_is_present(pdev)) + _scsih_flush_running_cmds(ioc);

_scsih_fw_event_cleanup_queue(ioc);

@@ -9992,8 +9992,8 @@ scsih_shutdown(struct pci_dev *pdev)

ioc->remove_host = 1;

- mpt3sas_wait_for_commands_to_complete(ioc); - _scsih_flush_running_cmds(ioc); + if (!pci_device_is_present(pdev)) + _scsih_flush_running_cmds(ioc);

_scsih_fw_event_cleanup_queue(ioc);