Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[Chris Mason]

Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
> From: Neil Horman <nhorman@tuxdriver.com>
> Date: Wed,  2 Mar 2011 11:28:22 -0500
> 
> > Recently had this bug halt reported to me:
> 
> Well, does anyone on the RDS team care about this bug fix at all?
> 
> Stuff like this should not sit for nearly a week without any reply
> whatsoever.
> 

The patch looks good to me, but I'm surprised we haven't seen it here.
Venkat please take a look (link to the patch below)  Has it only been seen on ppc?

http://permalink.gmane.org/gmane.linux.network/187933

-chris

Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[Neil Horman]

On Mon, Mar 07, 2011 at 03:41:04PM -0500, Chris Mason wrote:
> Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
> > From: Neil Horman <nhorman@tuxdriver.com>
> > Date: Wed,  2 Mar 2011 11:28:22 -0500
> > 
> > > Recently had this bug halt reported to me:
> > 
> > Well, does anyone on the RDS team care about this bug fix at all?
> > 
> > Stuff like this should not sit for nearly a week without any reply
> > whatsoever.
> > 
> 
> The patch looks good to me, but I'm surprised we haven't seen it here.
> Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
> 
Yes, its only been observed on ppc64.  Its does seem like it should be
observable on other arches.  I presumed it had something to do with ppc64
alignment and how it filled in the sg array, that led to a leftover bit of space
in the scattergather array.  Honestly though I wasnt too worried about ferreting
out the source, since it seemed apparent to me that buffers with
RDS_FLAG_CONG_BITMAP set were just causing rds_[loop|ib]_xmit to return a dummy
positive value (I say dummy because theres no actual data transmitted).  So I
figured if the value is just there to satisfy the return code, it might as well
also satisfy what is otherwise a valid BUG_ON check too.

Best
Neil

> http://permalink.gmane.org/gmane.linux.network/187933
> 
> -chris
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Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[David Miller]

From: Chris Mason <chris.mason@oracle.com>
Date: Mon, 07 Mar 2011 15:41:04 -0500

> Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
>> From: Neil Horman <nhorman@tuxdriver.com>
>> Date: Wed,  2 Mar 2011 11:28:22 -0500
>> 
>> > Recently had this bug halt reported to me:
>> 
>> Well, does anyone on the RDS team care about this bug fix at all?
>> 
>> Stuff like this should not sit for nearly a week without any reply
>> whatsoever.
>> 
> 
> The patch looks good to me, but I'm surprised we haven't seen it here.
> Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
> 
> http://permalink.gmane.org/gmane.linux.network/187933

Can I get an ACK or something, _please_?

Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[Chris Mason]

Excerpts from David Miller's message of 2011-03-08 13:52:23 -0500:
> From: Chris Mason <chris.mason@oracle.com>
> Date: Mon, 07 Mar 2011 15:41:04 -0500
> 
> > Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
> >> From: Neil Horman <nhorman@tuxdriver.com>
> >> Date: Wed,  2 Mar 2011 11:28:22 -0500
> >> 
> >> > Recently had this bug halt reported to me:
> >> 
> >> Well, does anyone on the RDS team care about this bug fix at all?
> >> 
> >> Stuff like this should not sit for nearly a week without any reply
> >> whatsoever.
> >> 
> > 
> > The patch looks good to me, but I'm surprised we haven't seen it here.
> > Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
> > 
> > http://permalink.gmane.org/gmane.linux.network/187933
> 
> Can I get an ACK or something, _please_?

Sorry, wasn't clear:

Acked-by: Chris Mason <chris.mason@oracle.com>

-chris

Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[David Miller]

From: Chris Mason <chris.mason@oracle.com>
Date: Tue, 08 Mar 2011 13:58:57 -0500

> Excerpts from David Miller's message of 2011-03-08 13:52:23 -0500:
>> From: Chris Mason <chris.mason@oracle.com>
>> Date: Mon, 07 Mar 2011 15:41:04 -0500
>> 
>> > Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
>> >> From: Neil Horman <nhorman@tuxdriver.com>
>> >> Date: Wed,  2 Mar 2011 11:28:22 -0500
>> >> 
>> >> > Recently had this bug halt reported to me:
>> >> 
>> >> Well, does anyone on the RDS team care about this bug fix at all?
>> >> 
>> >> Stuff like this should not sit for nearly a week without any reply
>> >> whatsoever.
>> >> 
>> > 
>> > The patch looks good to me, but I'm surprised we haven't seen it here.
>> > Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
>> > 
>> > http://permalink.gmane.org/gmane.linux.network/187933
>> 
>> Can I get an ACK or something, _please_?
> 
> Sorry, wasn't clear:
> 
> Acked-by: Chris Mason <chris.mason@oracle.com>

Applied, thanks everyone.

Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[Neil Horman]

On Tue, Mar 08, 2011 at 11:22:58AM -0800, David Miller wrote:
> From: Chris Mason <chris.mason@oracle.com>
> Date: Tue, 08 Mar 2011 13:58:57 -0500
> 
> > Excerpts from David Miller's message of 2011-03-08 13:52:23 -0500:
> >> From: Chris Mason <chris.mason@oracle.com>
> >> Date: Mon, 07 Mar 2011 15:41:04 -0500
> >> 
> >> > Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
> >> >> From: Neil Horman <nhorman@tuxdriver.com>
> >> >> Date: Wed,  2 Mar 2011 11:28:22 -0500
> >> >> 
> >> >> > Recently had this bug halt reported to me:
> >> >> 
> >> >> Well, does anyone on the RDS team care about this bug fix at all?
> >> >> 
> >> >> Stuff like this should not sit for nearly a week without any reply
> >> >> whatsoever.
> >> >> 
> >> > 
> >> > The patch looks good to me, but I'm surprised we haven't seen it here.
> >> > Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
> >> > 
> >> > http://permalink.gmane.org/gmane.linux.network/187933
> >> 
> >> Can I get an ACK or something, _please_?
> > 
> > Sorry, wasn't clear:
> > 
> > Acked-by: Chris Mason <chris.mason@oracle.com>
> 
> Applied, thanks everyone.
Thanks, Chris, Dave.
Neil

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Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

[Venkat Venkatsubra]

I was trying to recreate on our test systems. It's not a ppc.
So far not successful in crashing even though rds_ib_xmit hits this path: 
        /* Do not send cong updates to IB loopback */
        if (conn->c_loopback
            && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
                rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
                return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
        }

For the BUG_ON condition in rds_send_xmit:
ret=4096  conn->c_xmit_sg=1 rm->data.op_nents=2
BUG_ON(ret != 0 && conn->c_xmit_sg == rm->data.op.nents);

Venkat

----- Original Message -----
From: nhorman@tuxdriver.com
To: davem@davemloft.net
Cc: chris.mason@oracle.com, netdev@vger.kernel.org, rds-devel@oss.oracle.com, venkat.x.venkatsubra@oracle.com
Sent: Tuesday, March 8, 2011 1:36:50 PM GMT -06:00 US/Canada Central
Subject: Re: [rds-devel] [PATCH] rds: prevent BUG_ON triggering on congestion map updates

On Tue, Mar 08, 2011 at 11:22:58AM -0800, David Miller wrote:
> From: Chris Mason <chris.mason@oracle.com>
> Date: Tue, 08 Mar 2011 13:58:57 -0500
> 
> > Excerpts from David Miller's message of 2011-03-08 13:52:23 -0500:
> >> From: Chris Mason <chris.mason@oracle.com>
> >> Date: Mon, 07 Mar 2011 15:41:04 -0500
> >> 
> >> > Excerpts from David Miller's message of 2011-03-07 15:27:53 -0500:
> >> >> From: Neil Horman <nhorman@tuxdriver.com>
> >> >> Date: Wed,  2 Mar 2011 11:28:22 -0500
> >> >> 
> >> >> > Recently had this bug halt reported to me:
> >> >> 
> >> >> Well, does anyone on the RDS team care about this bug fix at all?
> >> >> 
> >> >> Stuff like this should not sit for nearly a week without any reply
> >> >> whatsoever.
> >> >> 
> >> > 
> >> > The patch looks good to me, but I'm surprised we haven't seen it here.
> >> > Venkat please take a look (link to the patch below)  Has it only been seen on ppc?
> >> > 
> >> > http://permalink.gmane.org/gmane.linux.network/187933
> >> 
> >> Can I get an ACK or something, _please_?
> > 
> > Sorry, wasn't clear:
> > 
> > Acked-by: Chris Mason <chris.mason@oracle.com>
> 
> Applied, thanks everyone.
Thanks, Chris, Dave.
Neil

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