On Wed, Feb 03, 1999 at 07:19:01PM +0100, Andi Kleen wrote:
> In article <19990203173256.B613@stefan.sime.com>,
> stefan@sime.com (Stefan Traby) writes:
> > Hi !
> > Linux 2.2.1 oopses after putting (silly) high values
> > into /proc/sys/net/core/[rw]mem_{default,max}.
>
> Linux 2.2 doesn't have per-user in-core memory limiting, although
> the basic infrastructure for it is there.
>
> Currently: don't do such stupid things as root.
According to my calculations my crash was *impossible*.
The values where high, but well calculated. The real stupid thing is in the
kernel.
I found the problem (in net/core/sock.c, SNDBUF-ioctl). The crash
occured because the system uses up to 2*sysctl_rmem_max.
---
if (val > sysctl_wmem_max)
val = sysctl_wmem_max;
sk->sndbuf = max(val*2,2048);
---
rmem_default = wmem_default = 64KB
rmem_max = wmem_max = 1MB
setsockopt(5, SOL_SOCKET, SO_SNDBUF, [1048576], 4) = 0
setsockopt(5, SOL_SOCKET, SO_RCVBUF, [1048576], 4) = 0
read(5, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 12338976) = 2009568
I really accept that SO_RCVBUF is a hint.
But I expect that sysctl_rmem_max is a hard limit that I can count on.
Somebody should really fix this or give me a good reason why that thing is
called *max.
Additional to the fix it would be to incrase the default values to 128KB
(because its the actual behavior).
--
ciao -
Stefan
Stefan Traby phone: +43-3133-6107-2
Mitterlasznitzstr. 13 fax: +43-3133-6107-9
8302 Nestelbach mailto://stefan@sime.com
Austria
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