[Bug 15007] New: SCSI host adapter's scatter-gather list size Issue

[Bug 15007] New: SCSI host adapter's scatter-gather list size Issue

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=15007

           Summary: SCSI host adapter's scatter-gather list size Issue
           Product: IO/Storage
           Version: 2.5
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: SCSI
        AssignedTo: linux-scsi@vger.kernel.org
        ReportedBy: nick.cheng@areca.com.tw
                CC: akpm@linux-foundation.org
        Regression: No


I found if I set scatter-gather table size as 1024 Areca's RAID controller,
ARC1680, and then execute "mkfs.ext3 /dev/sdX" on a sas/sata volume which is
formated as NTFS, it will kill the controller and let it restart.
This issue pops up easily on Intel server board with multi-processors and so
far can not be reproduced on a volume with a original Linux filesystem such as,
ext3.
I also found the issue is on the write command with 128 sg entries, each with
4K byte in length. As the command comes from the upper layer, it lacks data in
the 128th sg entry.
I exits from 2.6.18 to 2.6.32.
I try to track kernel source code but so far there is no finding.
The driver is
ftp://ftp.areca.com.tw/RaidCards/AP_Drivers/Linux/DRIVER/SourceCode/arcmsr.1.20.0X.15-90605.zip.
Anybody can give it a try??
Thanks,

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007


nick cheng <nick.cheng@areca.com.tw> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nick.cheng@areca.com.tw
     Kernel Version|                            |2.6.32




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Re: [Bug 15007] New: SCSI host adapter's scatter-gather list size Issue

[FUJITA Tomonori]

On Fri, 8 Jan 2010 11:07:49 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
>            Summary: SCSI host adapter's scatter-gather list size Issue
>            Product: IO/Storage
>            Version: 2.5
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: SCSI
>         AssignedTo: linux-scsi@vger.kernel.org
>         ReportedBy: nick.cheng@areca.com.tw
>                 CC: akpm@linux-foundation.org
>         Regression: No
> 
> 
> I found if I set scatter-gather table size as 1024 Areca's RAID controller,

You mean that setting sg_tablesize in scsi_host_template to 1024?


> ARC1680, and then execute "mkfs.ext3 /dev/sdX" on a sas/sata volume which is
> formated as NTFS, it will kill the controller and let it restart.
> This issue pops up easily on Intel server board with multi-processors and so
> far can not be reproduced on a volume with a original Linux filesystem such as,
> ext3.

Can your controller hardware and firmware handle 1024 scatter gather
entries?


> I also found the issue is on the write command with 128 sg entries, each with
> 4K byte in length. As the command comes from the upper layer, it lacks data in
> the 128th sg entry.

The device driver really get 128 entries?

How can you issue a write command with 128 sg entries?

Even if your user-space application issues a write command with 128 sg
entries, the device driver could get less sg entries.

If the device driver gets a command including 128 sg entries
(cmd->sdb.table.nents is set to 128) and 128th sg entry doesn't have
data, then probably we have a bug in scatter gather or block layer
code.

[Bug 15007] SCSI host adapter's scatter-gather list size Issue

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #1 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2010-01-14 08:25:25 ---
Reply-To: fujita.tomonori@lab.ntt.co.jp

On Fri, 8 Jan 2010 11:07:49 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
>            Summary: SCSI host adapter's scatter-gather list size Issue
>            Product: IO/Storage
>            Version: 2.5
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: SCSI
>         AssignedTo: linux-scsi@vger.kernel.org
>         ReportedBy: nick.cheng@areca.com.tw
>                 CC: akpm@linux-foundation.org
>         Regression: No
> 
> 
> I found if I set scatter-gather table size as 1024 Areca's RAID controller,

You mean that setting sg_tablesize in scsi_host_template to 1024?


> ARC1680, and then execute "mkfs.ext3 /dev/sdX" on a sas/sata volume which is
> formated as NTFS, it will kill the controller and let it restart.
> This issue pops up easily on Intel server board with multi-processors and so
> far can not be reproduced on a volume with a original Linux filesystem such as,
> ext3.

Can your controller hardware and firmware handle 1024 scatter gather
entries?


> I also found the issue is on the write command with 128 sg entries, each with
> 4K byte in length. As the command comes from the upper layer, it lacks data in
> the 128th sg entry.

The device driver really get 128 entries?

How can you issue a write command with 128 sg entries?

Even if your user-space application issues a write command with 128 sg
entries, the device driver could get less sg entries.

If the device driver gets a command including 128 sg entries
(cmd->sdb.table.nents is set to 128) and 128th sg entry doesn't have
data, then probably we have a bug in scatter gather or block layer
code.

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #2 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 10:54:42 ---
Thanks for reply.
I am sure that hardware and firmware can handle 1024 scatter gather
entries.
I can not limit the AP to dispatch a write command with 128 sg entries.
I just execute mkfs.ext3 /dev/sdX and print it out as the sg entry number is
128. I found the 128th entry indeed has no data.

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Re: [Bug 15007] SCSI host adapter's scatter-gather list size Issue

[FUJITA Tomonori]

On Thu, 14 Jan 2010 10:54:44 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #2 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 10:54:42 ---
> Thanks for reply.
> I am sure that hardware and firmware can handle 1024 scatter gather
> entries.
> I can not limit the AP to dispatch a write command with 128 sg entries.
> I just execute mkfs.ext3 /dev/sdX and print it out as the sg entry number is
> 128. I found the 128th entry indeed has no data.

So 'no data sg entry' is the cause of hardware reset?

>From a quick look at the driver, I found one bug about scatter-gather
handling.

static int arcmsr_build_ccb(struct AdapterControlBlock *acb,struct
CommandControlBlock *ccb,struct scsi_cmnd *pcmd)
{
(snip)...
					arccdbsize += sizeof(struct SG32ENTRY);
				}else{
					struct SG64ENTRY *pdma_sg = (struct SG64ENTRY *)psge;

					pdma_sg->addresshigh = address_hi;
					pdma_sg->address = address_lo;
					pdma_sg->length = length|cpu_to_le32(IS_SG64_ADDR);
					psge += sizeof(struct SG64ENTRY);
					arccdbsize += sizeof(struct SG64ENTRY);
				}
				sl++;

The last line doesn't work. Use sl = sg_next(sl); Using
scsi_for_each_sg() is even better (as the driver in mainline
does). With this bug, 129th sg entry is broken. If your analysis is
correct, there should be other bugs..

[Bug 15007] SCSI host adapter's scatter-gather list size Issue

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #3 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2010-01-14 11:12:21 ---
Reply-To: fujita.tomonori@lab.ntt.co.jp

On Thu, 14 Jan 2010 10:54:44 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #2 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 10:54:42 ---
> Thanks for reply.
> I am sure that hardware and firmware can handle 1024 scatter gather
> entries.
> I can not limit the AP to dispatch a write command with 128 sg entries.
> I just execute mkfs.ext3 /dev/sdX and print it out as the sg entry number is
> 128. I found the 128th entry indeed has no data.

So 'no data sg entry' is the cause of hardware reset?

>From a quick look at the driver, I found one bug about scatter-gather
handling.

static int arcmsr_build_ccb(struct AdapterControlBlock *acb,struct
CommandControlBlock *ccb,struct scsi_cmnd *pcmd)
{
(snip)...
                    arccdbsize += sizeof(struct SG32ENTRY);
                }else{
                    struct SG64ENTRY *pdma_sg = (struct SG64ENTRY *)psge;

                    pdma_sg->addresshigh = address_hi;
                    pdma_sg->address = address_lo;
                    pdma_sg->length = length|cpu_to_le32(IS_SG64_ADDR);
                    psge += sizeof(struct SG64ENTRY);
                    arccdbsize += sizeof(struct SG64ENTRY);
                }
                sl++;

The last line doesn't work. Use sl = sg_next(sl); Using
scsi_for_each_sg() is even better (as the driver in mainline
does). With this bug, 129th sg entry is broken. If your analysis is
correct, there should be other bugs..

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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--- Comment #4 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 12:27:11 ---
Sorry, is it a really bug?
Does it bug anything? I can't figure it out.
I ever used scsi_for_each_sg() and found the performance is inferior to the
original version. I tracked the source code for scsi_for_each_sg()and there is
no two much difference to each other. I doubt it is compiler issue to make it
worst.
But it is my guess. Do you know why? 
Anyway, will you or anybody take care of this issue?
Thank you again,

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Re: [Bug 15007] SCSI host adapter's scatter-gather list size Issue

[FUJITA Tomonori]

On Thu, 14 Jan 2010 12:27:12 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #4 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 12:27:11 ---
> Sorry, is it a really bug?

Yes because if sg entries are larger than 127, they are not
continuous. So sg++ doesn't work. We chain sg entries. The last sg
entry is a pointer to the next sg list.

For example, a command has 128 entries, it has two sg lists. The first
sg list has 127 sg entries. The last entry in the first sg list is a
pointer to the second sg list. The second sg list has one sg
entry. The command has 128 entries in total.

My previous mail is partially wrong. As I explained above, if sg
entries is 128, this bug leads to bogus 128th sg entry. So I think
that you hit this bug.


> Does it bug anything? I can't figure it out.
> I ever used scsi_for_each_sg() and found the performance is inferior to the
> original version. I tracked the source code for scsi_for_each_sg()and there is
> no two much difference to each other. I doubt it is compiler issue to make it
> worst.
> But it is my guess. Do you know why? 
> Anyway, will you or anybody take care of this issue?

[Bug 15007] SCSI host adapter's scatter-gather list size Issue

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #5 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2010-01-14 12:49:54 ---
Reply-To: fujita.tomonori@lab.ntt.co.jp

On Thu, 14 Jan 2010 12:27:12 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #4 from nick cheng <nick.cheng@areca.com.tw>  2010-01-14 12:27:11 ---
> Sorry, is it a really bug?

Yes because if sg entries are larger than 127, they are not
continuous. So sg++ doesn't work. We chain sg entries. The last sg
entry is a pointer to the next sg list.

For example, a command has 128 entries, it has two sg lists. The first
sg list has 127 sg entries. The last entry in the first sg list is a
pointer to the second sg list. The second sg list has one sg
entry. The command has 128 entries in total.

My previous mail is partially wrong. As I explained above, if sg
entries is 128, this bug leads to bogus 128th sg entry. So I think
that you hit this bug.


> Does it bug anything? I can't figure it out.
> I ever used scsi_for_each_sg() and found the performance is inferior to the
> original version. I tracked the source code for scsi_for_each_sg()and there is
> no two much difference to each other. I doubt it is compiler issue to make it
> worst.
> But it is my guess. Do you know why? 
> Anyway, will you or anybody take care of this issue?

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #6 from nick cheng <nick.cheng@areca.com.tw>  2010-01-15 02:49:48 ---
OK. I got it.
But based on 128 sg entries issue on my original driver I found it bugs every
time while doing mkfs.ext3 on a default NTFS filesystem, but if I do it on a
ext3 filesystem, it works smoothly.
Besides, it bugs on SMP platforms always but doesn't on non-SMP plaform.
Can your inference explain it?
Thanks so much for your help.

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #7 from nick cheng <nick.cheng@areca.com.tw>  2010-01-15 12:23:13 ---
Hi,
I got one more question.
What does sg_tablesize in scsi_host_template mean?
It means the max sg entry number which the HW can handle once?
I collect the sg table size from upper layer while I do mkfs.ext3.
The maximum number is circa one eighth of sg_tablesize.
Thanks for your reply in advance.

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Re: [Bug 15007] SCSI host adapter's scatter-gather list size Issue

[FUJITA Tomonori]

On Fri, 15 Jan 2010 02:49:53 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #6 from nick cheng <nick.cheng@areca.com.tw>  2010-01-15 02:49:48 ---
> OK. I got it.
> But based on 128 sg entries issue on my original driver I found it bugs every
> time while doing mkfs.ext3 on a default NTFS filesystem, but if I do it on a
> ext3 filesystem, it works smoothly.

Do you mean that 128 sg entries don't cause any problems during
performing mkfs on ext3? If so, I have no idea.


> Besides, it bugs on SMP platforms always but doesn't on non-SMP plaform.
> Can your inference explain it?

Do you mean that 128 sg entries don't cause any problems on non SMP
boxes? If so, I have no idea. Your driver should hit this bug with any
boxes.

Re: [Bug 15007] SCSI host adapter's scatter-gather list size Issue

[FUJITA Tomonori]

On Fri, 15 Jan 2010 12:23:16 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> What does sg_tablesize in scsi_host_template mean?
> It means the max sg entry number which the HW can handle once?

Yes. A driver should set it to hardware limit.

Can you close this bug report on bugzilla.kernel.org? The bug is not
in mainline. If you have any further questions related with this
topic, please send to linux-scsi mailing list instead of using the
kernel bug tracker.

Thanks,

[Bug 15007] SCSI host adapter's scatter-gather list size Issue

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #8 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2010-01-18 04:18:08 ---
Reply-To: fujita.tomonori@lab.ntt.co.jp

On Fri, 15 Jan 2010 02:49:53 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=15007
> 
> 
> 
> 
> 
> --- Comment #6 from nick cheng <nick.cheng@areca.com.tw>  2010-01-15 02:49:48 ---
> OK. I got it.
> But based on 128 sg entries issue on my original driver I found it bugs every
> time while doing mkfs.ext3 on a default NTFS filesystem, but if I do it on a
> ext3 filesystem, it works smoothly.

Do you mean that 128 sg entries don't cause any problems during
performing mkfs on ext3? If so, I have no idea.


> Besides, it bugs on SMP platforms always but doesn't on non-SMP plaform.
> Can your inference explain it?

Do you mean that 128 sg entries don't cause any problems on non SMP
boxes? If so, I have no idea. Your driver should hit this bug with any
boxes.

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007





--- Comment #9 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2010-01-18 04:18:16 ---
Reply-To: fujita.tomonori@lab.ntt.co.jp

On Fri, 15 Jan 2010 12:23:16 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

> What does sg_tablesize in scsi_host_template mean?
> It means the max sg entry number which the HW can handle once?

Yes. A driver should set it to hardware limit.

Can you close this bug report on bugzilla.kernel.org? The bug is not
in mainline. If you have any further questions related with this
topic, please send to linux-scsi mailing list instead of using the
kernel bug tracker.

Thanks,

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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http://bugzilla.kernel.org/show_bug.cgi?id=15007


nick cheng <nick.cheng@areca.com.tw> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WILL_NOT_FIX
         Regression|No                          |Yes




--- Comment #10 from nick cheng <nick.cheng@areca.com.tw>  2010-01-18 09:41:58 ---
(In reply to comment #9)
> Reply-To: fujita.tomonori@lab.ntt.co.jp
> 
> On Fri, 15 Jan 2010 12:23:16 GMT
> bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> > What does sg_tablesize in scsi_host_template mean?
> > It means the max sg entry number which the HW can handle once?
> 
> Yes. A driver should set it to hardware limit.
> 
> Can you close this bug report on bugzilla.kernel.org? The bug is not
> in mainline. If you have any further questions related with this
> topic, please send to linux-scsi mailing list instead of using the
> kernel bug tracker.
> 
> Thanks,
OK

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[Bug 15007] SCSI host adapter's scatter-gather list size Issue

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--- Comment #11 from nick cheng <nick.cheng@areca.com.tw>  2010-01-18 09:45:32 ---
(In reply to comment #8)
> Reply-To: fujita.tomonori@lab.ntt.co.jp
> 
> On Fri, 15 Jan 2010 02:49:53 GMT
> bugzilla-daemon@bugzilla.kernel.org wrote:
> 
> > http://bugzilla.kernel.org/show_bug.cgi?id=15007
> > 
> > 
> > 
> > 
> > 
> > --- Comment #6 from nick cheng <nick.cheng@areca.com.tw>  2010-01-15 02:49:48 ---
> > OK. I got it.
> > But based on 128 sg entries issue on my original driver I found it bugs every
> > time while doing mkfs.ext3 on a default NTFS filesystem, but if I do it on a
> > ext3 filesystem, it works smoothly.
> 
> Do you mean that 128 sg entries don't cause any problems during
> performing mkfs on ext3? If so, I have no idea.
> Yes, so far 128 sg entries don't cause any problems.
> 
> > Besides, it bugs on SMP platforms always but doesn't on non-SMP plaform.
> > Can your inference explain it?
> 
> Do you mean that 128 sg entries don't cause any problems on non SMP
> boxes? If so, I have no idea. Your driver should hit this bug with any
> boxes.

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