cvs commit: src/sys/vm vm_kern.c
Mike Silbersack
silby at silby.com
Mon Feb 16 18:08:50 PST 2004
On Tue, 17 Feb 2004, Colin Percival wrote:
> At 21:05 16/02/2004, Maxime Henrion wrote:
> >I find it very convenient to have a flag to tell malloc() to try as hard
> >as it can to allocate the memory without crashing on us.
>
> <hat="kernel newbie">
> Is this really good enough? When I was routinely running my system out
> of kernel memory by using a large malloc backed md(4), the panic never
> came from a failed allocation in the md code; rather, md would use up all
> the available memory, and then some other kernel call (which needed only
> some small amount of memory) would panic.
> From a security point of view, I can't see how there's any alternative
> to using a user-allocated buffer for such requests.
> </hat>
>
> Colin Percival
The M_SAFE and M_NOWAIT flags could be set to leave a 10% memory buffer
that only M_WAITOK callers would eat into. This would (hopefully) help to
avoid panicing the system, while still maintaining the desired semantic
for M_WAITOK callers.
Er, wait, maybe M_WAITOK callers should block at that boundary, and
M_NOWAIT should succeed... hrm.
Either way, something should be done, the current state of affairs isn't
all that perfect.
Mike "Silby" Silbersack
More information about the cvs-all
mailing list