Dear Linux folks,
Could you please apply commit 0c25422d34b4 (scsi: mpt3sas: Remove
scsi_dma_map() error messages) to the 5.15.y series?
commit 0c25422d34b4726b2707d5f38560943155a91b80
Author: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>
Date: Thu Mar 3 19:32:03 2022 +0530
scsi: mpt3sas: Remove scsi_dma_map() error messages
When scsi_dma_map() fails by returning a sges_left value less than
zero,
the amount of logging produced can be extremely high. In a recent
end-user
environment, 1200 messages per second were being sent to the log
buffer.
This eventually overwhelmed the system and it stalled.
These error messages are not needed. Remove them.
Link:
https://lore.kernel.org/r/20220303140203.12642-1-sreekanth.reddy@xxxxxxxxxxxx
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Sreekanth Reddy <sreekanth.reddy@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
We see this regression after upgrading from Linux 5.10 to 5.15 on our
file servers with Broadcom/LSI SAS3008 PCI-Express Fusion-MPT SAS-3
(mpt3sas) – though luckily our systems do not stall/crash.
The commit message does not say anything about, what commit caused these
error to be appearing – the log statements have been there since
v4.20-rc1, if I am not mistaken, so it must be something else –, and
also do not mention, why these log messages are not needed, but the new
error condition is actually expected.
In the Canonical/Ubuntu bug tracker I found the explanation below [2].
2. mpt3sas: Remove scsi_dma_map errors messages:
When driver set the DMA mask to 32bit then we observe that the
SWIOTLB bounce buffers are getting exhausted quickly. For most of the
IOs driver observe that scsi_dma_map() API returned with failure
status and hence driver was printing below error message. Since this
error message is getting printed per IO and if user issues heavy IOs
then we observe that kernel overwhelmed with this error message. Also
we will observe the kernel panic when the serial console is enabled.
So to limit this issue, we removed this error message though this
patch.
"scsi_dma_map failed: request for 1310720 bytes!"
The Launchpad issue was created in March 2022, and the fixed Linux
kernel package 5.15.0-53.59 for Ubuntu 22.04 released on November 15th,
2022.
Sreekanth, looking again, you are the patch author, one of the Broadcom
maintainers (LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)) and created the
Launchpad bug report. I am surprised you didn’t get it backported upstream.
Kind regards,
Paul
[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=master&id=0c25422d34b4726b2707d5f38560943155a91b80
[2]: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1965927
"[Ubuntu 22.04] mpt3sas: Request to include latest bug fix patches"
