Date: Sun, 23 Jun 2002 15:33:46 -0500 (CDT) From: Jonathan Lemon <jlemon@flugsvamp.com> To: don@sandvine.com, stable@freebsd.org Cc: jlemon@flugsvamp.com Subject: Re: panic in syncache/rtfree with 4.6 Message-ID: <200206232033.g5NKXkJ46469@prism.flugsvamp.com> In-Reply-To: <local.mail.freebsd-stable/FE045D4D9F7AED4CBFF1B3B813C85337676579@mail.sandvine.com>
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In article <local.mail.freebsd-stable/FE045D4D9F7AED4CBFF1B3B813C85337676579@mail.sandvine.com> you write:
>
>Has anyone else seen anything like this...
>
>panic(c0334f20,c392e400,ff807f44,c021fd76,c392e400) at panic+0xa4
>rtfree(c392e400) at rtfree+0x27
>syncache_free(debe8fc0,62000000,debe8fc0,1,debe8660) at syncache_free+0x56
>syncache_drop(debe8fc0,0,1,c0220118,40000000) at syncache_drop+0xd8
>syncache_timer(1,40000000,0,0,ffffffff) at syncache_timer+0xa8
>softclock(0,ff800018,10,c0390010,ffffffff) at softclock+0xd1
>doreti_swi() at doreti_swi+0xf
>
>The system is running 4.6. There were messages that immediately
>preceeded this about 'All mbuf clusters exhausted, please see tuning(7).'.
>
>Does it seem reasonable to get a panic in this circumstance?
No. What does the panic message say? Do you happen to have a kernel
coredump + kernel somewhere to take a look at?
The offset of the crash within rtfree() seems to indicate that you've
triggered the first panic, which would only be the case here if rnh == NULL:
struct radix_node_head *rnh =
rt_tables[rt_key(rt)->sa_family];
The panic dump would show if sa_family was garbage for some reason.
>I'm expecting to keep ~35K TCP sessions open on this device. Is syncache
>appropriate, or should I disable and use an external device to protect
>against DOS?
Yup, syncache only applies to new SYNs (unsynchronized connections), it
doesn't matter how many existing open connections you have. Your syncache
statistics (the net.inet.tcp.syncache.count entry) show that you don't
have any entries in your syncache at the moment.
--
Jonathan
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