kern/53350: fill up a malloc md-disk on 5.1-R causes panic

[Jason Kuri]

The following reply was made to PR kern/53350; it has been noted by GNATS.

From: Jason Kuri <jay at oneway.com>
To: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
Cc: FreeBSD-gnats-submit at freebsd.org
Subject: Re: kern/53350: fill up a malloc md-disk on 5.1-R causes panic 
Date: Sun, 15 Jun 2003 11:32:41 -0500

 Hi there,
 
 That makes sense... but hold on a sec.
 
 I have 256M of ram, and try to use 110M for malloc-disk, and my machine 
 panics?  That seems awfully broken to me.  This is single user mode, 
 nothing else is running.  Why does 110M of MD-disk cause a 256M machine 
 to run out of memory?   I should have 140M or so left for the system to 
 play with...   If nothing else,  shouldn't it at least fail and not 
 panic the system?
 
 This worked fine 1 month ago. (5.0-Current from APR-30)
 
 Jay
 
 
 
 
 On Sunday, June 15, 2003, at 11:24  AM, Poul-Henning Kamp wrote:
 
 >>> Description:
 >>          If you have a 5.1-R system with, say, 256M of ram
 >> and you mdconfig one or several malloc md-devices totalling around 
 >> 100M,
 >> if you attempt to use them to capacity, the machine will panic.  The
 >> message given is:
 >>
 >> panic: kmem_malloc(4096): kmem_map too small: 108347392 total 
 >> allocated
 >
 > It's really very simple:  You ran out of kernel mapped memory ("KVM").
 >
 > Remedy: Don't Do That.
 >
 > See also: malloc(9), md(4)
 >
 > This PR can be closed.
 >
 > -- 
 > Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
 > phk at FreeBSD.ORG         | TCP/IP since RFC 956
 > FreeBSD committer       | BSD since 4.3-tahoe
 > Never attribute to malice what can adequately be explained by 
 > incompetence.
 >