Debug scsi message in linux 4.19.31

Debug scsi message in linux 4.19.31

[Hussam Al-Tayeb]

Hi. I'm seeing a debug message in linux stable kernel 4.19.31 with this
patch
scsi-sd-optimal-i-o-size-should-be-a-multiple-of-physical-block-
size.patch

I am getting:
Mar 23 17:40:10 hades kernel: sd 0:0:0:0: [sda] Optimal transfer size 0
bytes < PAGE_SIZE (4096 bytes)
Mar 23 17:40:10 hades kernel: sd 2:0:0:0: [sdb] Optimal transfer size 0
bytes < PAGE_SIZE (4096 bytes)
Mar 23 17:46:43 hades kernel: sd 4:0:0:0: [sdc] Optimal transfer size 0
bytes < PAGE_SIZE (4096 bytes)

sda and sdb are physically attached SATA mechanical disks (Western
Digital and Seagate, respectively).
sdc is a kingston usb flash drive. All three disks use ext4 luks
encrypted partitions.
Is the fact that it is reporting 0 as optimal transfer size something I
should worry about? Note that the the three storage devices are from
three different manufacturers.
This particular machine is a Lenovo Intel(R) Core(TM) i5-6400 CPU @
2.70GHz with 16GB Kingston DDR4 ram.

I tried moving the root disk to another machine (a DELL Core I7 7700
with slightly faster ram from Samsung) and I saw the same message.

This seems like a patch that fits better in a hardware vendor or
operating system distributor tree than the upstream kernel. Shouldn't
stable tree kernels only contain direct fixes and regression fixes?
Does it really belong in an LTS kernel?

Please CC me in your reply as I am not subscribed to the list.
Thank you.

Re: Debug scsi message in linux 4.19.31

[Randy Dunlap]

[adding linux-scsi and mkp]

On 3/24/19 6:07 AM, Hussam Al-Tayeb wrote:
> Hi. I'm seeing a debug message in linux stable kernel 4.19.31 with this
> patch
> scsi-sd-optimal-i-o-size-should-be-a-multiple-of-physical-block-
> size.patch
> 
> I am getting:
> Mar 23 17:40:10 hades kernel: sd 0:0:0:0: [sda] Optimal transfer size 0
> bytes < PAGE_SIZE (4096 bytes)
> Mar 23 17:40:10 hades kernel: sd 2:0:0:0: [sdb] Optimal transfer size 0
> bytes < PAGE_SIZE (4096 bytes)
> Mar 23 17:46:43 hades kernel: sd 4:0:0:0: [sdc] Optimal transfer size 0
> bytes < PAGE_SIZE (4096 bytes)
> 
> sda and sdb are physically attached SATA mechanical disks (Western
> Digital and Seagate, respectively).
> sdc is a kingston usb flash drive. All three disks use ext4 luks
> encrypted partitions.
> Is the fact that it is reporting 0 as optimal transfer size something I
> should worry about? Note that the the three storage devices are from
> three different manufacturers.
> This particular machine is a Lenovo Intel(R) Core(TM) i5-6400 CPU @
> 2.70GHz with 16GB Kingston DDR4 ram.
> 
> I tried moving the root disk to another machine (a DELL Core I7 7700
> with slightly faster ram from Samsung) and I saw the same message.
> 
> This seems like a patch that fits better in a hardware vendor or
> operating system distributor tree than the upstream kernel. Shouldn't
> stable tree kernels only contain direct fixes and regression fixes?
> Does it really belong in an LTS kernel?
> 
> Please CC me in your reply as I am not subscribed to the list.
> Thank you.
> 


-- 
~Randy

Re: Debug scsi message in linux 4.19.31

[Martin K. Petersen]

Randy,

>> Mar 23 17:40:10 hades kernel: sd 0:0:0:0: [sda] Optimal transfer size 0
>> bytes < PAGE_SIZE (4096 bytes)

We're just trying to weed out the devices that report garbage in this
field. But of course none of the devices I tested with put 0 in there.

>> Does it really belong in an LTS kernel?

The patch does fix problems for devices that report a nonsensical
value. But it is a regression that it now prints a warning for devices
that don't report an optimal I/O size at all.

Sorry about that. Will fix tomorrow!

-- 
Martin K. Petersen	Oracle Linux Engineering