Re: [PATCH] shm: fix a race between shm_exit() and shm_init()

Kay Sievers
2011-08-03T13:33:55Z

On Wed, Aug 3, 2011 at 15:13, Thadeu Lima de Souza Cascardo
<cascardo@minaslivre.org> wrote:
> As Marc Zyngier has pointed out, the culprit is driver_init, which
> calls devices_init. I'd say other calls from driver_init also call into
> kset and kobject, which will dispatch uevent helper.
>
> I tried to reproduce the problem using UML and only was successful after
> setting CONFIG_UEVENT_HELPER_PATH. I guess we could obsolete this
> feature and plan its removal soon. Is anybody still using this?

Forking binaries from the kernel for frequent events is something
fundamentally wrong to do. It is not even rate-limited or has any
upper bounds. It is known to create out-of-memory situations on
machines with many devices and tiny RAM. Configs that virtualizations
with many guests use pretty often. They can not even bootup with
/sbin/hotplug enabled then.

It would be nice to remove that broken thing, no common system or
distro uses it since quite some years now. But I wouldn't be surprised
if some people still use it for whatever hack they need locally.

Kay