[CentOS] CentOS-4 Xen kernel with low RAM and Badness in local_bh_enable at kernel/softirq.c:141

I have small xen VM running centos4 which acts as a router/firewall, and has
been working fine for over 1.5 years with 32MB of RAM and a kernel I either
got from xensource.org or built myself from their sources. (centos 4 didn't
have a xen kernel back then)

I lost the kernel to a corrupted disk and decided to use the centos provided
xen kernel.

All these months 32MB + 64MB Swap was more than sufficient and I never had
any problems.(3-digit uptimes) The CentOS Xen kernel is unusable at 32MB and
invokes the OOM killer even though there is plenty of swap free (and about
5-10MB of RAM too). After the OOM killer has done it's job there's about 15MB
of RAM free and swap is hardly used at all (1MB at most)

I've increased RAM to 64MB and the OOM killer doesn't kick in.. but I am
seeing plenty of such messages in the logs ...

Dec  2 16:05:21 noc kernel: Badness in local_bh_enable at kernel/softirq.c:141
Dec  2 16:05:21 noc kernel:  [<c0121178>] local_bh_enable+0x47/0x6f
Dec  2 16:05:21 noc kernel:  [<c02177d5>] skb_checksum+0x133/0x25e
Dec  2 16:05:21 noc kernel:  [<c0250f06>] udp_poll+0x66/0x113
Dec  2 16:05:21 noc kernel:  [<c02135fd>] sock_poll+0x19/0x1d
Dec  2 16:05:21 noc kernel:  [<c016d1a6>] do_select+0x190/0x2c7
Dec  2 16:05:21 noc kernel:  [<c016ceb5>] __pollwait+0x0/0x9b
Dec  2 16:05:21 noc kernel:  [<c0144ae4>] __kmalloc+0x56/0xd3
Dec  2 16:05:21 noc kernel:  [<c016d5dc>] sys_select+0x2e7/0x45c
Dec  2 16:05:21 noc kernel:  [<c010740f>] syscall_call+0x7/0xb

Any idea what's causing it / how to make it stop ?

I'm running Centos 5 in Dom0 and CentOS 4 in the router domU and there's
another couple of Centos 5 domU which is running error free.

Kingsly

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