Re: Kernel Tainted

On 10/05/2016 08:41 PM, reiner peterke wrote:
> Hi,
>
> We are helping a client test an application On Power8 using Postgres
> 9.5.4 which has been compiled specifically for the Power.
>
> This is running on sles12sp1  the current kernel is 3.12.49-11
>
> We are getting these kernel warning associated with the postmaster
> process.  The application is handling around 15000TPS  It appears that
> one of these messages is generated for each each transaction which fills
> up the warn.log quite quickly.
>
> I’m trying to understand what is causing the Tainted kernel messages.
> the warning is at 'WARNING: at ../net/core/dst.c:287’.
> I’ve found one link that indicates that this is ip6 related.
>  https://brunomgalmeida.wordpress.com/2015/07/23/disable-ipv6-postgres-and-pgbouncer/
> Is this accurate?  And if these action resolve the error, is it more of
> a bandaid then an actual fix?
>

As Andres already pointed out, this is most likely a kernel issue, not a 
PostgreSQL one. The "tainted" has nothing to do with the cause, it's 
just a way to inform users whether it's a clean kernel build, or if it 
includes code not available in vanilla kernels etc. The "X" means there 
are some SuSe-specific modules loaded, IIRC.

And yes, it seems IPv6 related, at least judging by the stack trace:

0xc0000000016f7d80 (unreliable)
sk_dst_check+0x174/0x180
ip6_sk_dst_lookup_flow+0x4c/0x2a0
udpv6_sendmsg+0x688/0xb20
inet_sendmsg+0x9c/0x120
sock_sendmsg+0xec/0x140
SyS_sendto+0x108/0x150
SyS_send+0x50/0x70
SyS_socketcall+0x2a0/0x440
syscall_exit+0x0/0x7c

You should probably talk to SuSe or whoever supports that system.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services