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Date:      Fri, 31 Dec 1999 02:35:33 +0200 (IST)
From:      Roman Shterenzon <roman@xpert.com>
To:        Bosko Milekic <bmilekic@dsuper.net>
Cc:        "Mr. K." <bsd@inbox.org>, stable@FreeBSD.ORG
Subject:   Re: Panic: Out of mbuf clusters
Message-ID:  <Pine.BSF.4.21.9912310232360.85199-100000@rs.ksl.co.il>
In-Reply-To: <Pine.OSF.4.05.9912301855340.29156-100000@oracle.dsuper.net>

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Good day,

That's very scary, that means that a individual or group of individuals
having a decent intenet link could bring a FreeBSD-stable machine to it's
knees. Please correct me if I'm wrong.
Is there nmbcluster number which cannot be exploited using current (I
don't mean freebsd-current :) technology?

On Thu, 30 Dec 1999, Bosko Milekic wrote:

> 
> On Thu, 30 Dec 1999, Mr. K. wrote:
> 
> !>OK, so I raised NMBCLUSTERS to 4096, and installed a second freebsd-stable
> !>box also with NMBCLUSTERS at 4096, and I managed to have them both panic
> !>at the same time (unfortunately, only one of them gave me a crash dump).
> !>But anyway, here is the stack trace, hopefully someone can tell me if this
> !>is the same as the known problem, and whether 4.0 would fix it.
> !>
> !>euclid# cd /var/crash
> !>euclid# ls
> !>bounds          kernel.0        minfree         vmcore.0
> !>euclid# gdb -k kernel.0 vmcore.0 
> !>GNU gdb 4.18
> !>Copyright 1998 Free Software Foundation, Inc.
> !>GDB is free software, covered by the GNU General Public License, and you
> !>are
> !>welcome to change it and/or distribute copies of it under certain
> !>conditions.
> !>Type "show copying" to see the conditions.
> !>There is absolutely no warranty for GDB.  Type "show warranty" for
> !>details.
> !>This GDB was configured as "i386-unknown-freebsd"...
> !>IdlePTD 2392064
> !>initial pcb at 1e64a4
> !>panicstr: Out of mbuf clusters
> !>panic messages:
> !>---
> !>panic: Ouxl0: no memory for rx list -- packet dropped!
> !>t of mbuf clusters
> !>
> 
> [snip]
> 
> !>---
> !>#0  0xc01253bb in boot ()
> !>(kgdb) where
> !>#0  0xc01253bb in boot ()
> !>#1  0xc0125640 in at_shutdown ()
> !>#2  0xc013b5ca in m_retryhdr ()
> !>#3  0xc013d283 in sosend ()
> !>#4  0xc01333e8 in soo_write ()
> !>#5  0xc0130332 in dofilewrite ()
> !>#6  0xc013023b in write ()
> !>#7  0xc01ac6a7 in syscall ()
> !>#8  0xc019fdcc in Xint0x80_syscall ()
> !>#9  0x8048983 in ?? ()
> !>#10 0x8048679 in ?? ()
> !>(kgdb)
> 
> 
> 	Well, now. We can see that the actual panic occurs during a send()
>   syscall (and not as a result of anything in the driver). Since sosend()
>   calls the allocation routines with M_WAIT, this confirms the origin of
>   the panic.
>   	At the same time, you can observe that the `xl' driver is
>   properly dropping packets when it runs out of memory. The panic problem
>   is solved in -CURRENT. However, if you ever see such messages as "no
>   memory for [...]" and it's coming from the `xl' driver, that's a good
>   indication -- assuming that this occurs often -- that you should higher
>   NMBCLUSTERS. 
> 
>   Bosko.
> 
> --
>  Bosko Milekic
>  Email:  bmilekic@dsuper.net
>  WWW:    http://pages.infinit.net/bmilekic/
> --
> 
> 
> 
> 
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> 

--Roman Shterenzon, UNIX System Administrator and Consultant
[ Xpert UNIX Systems Ltd., Herzlia, Israel. Tel: +972-9-9522361 ]



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