From: Prarit Bhargava <prarit@sgi.com>
To: linux-hotplug@vger.kernel.org
Subject: Virtual Console Hotplug Leads to OOM
Date: Wed, 30 Mar 2005 16:30:23 +0000 [thread overview]
Message-ID: <424AD41F.1040309@sgi.com> (raw)
Colleagues,
I've identified the following critical issue where the hotplug subsystem
can cause OOM-killer to run. IMO this is a critical issue within
hotplug -- in the case below, only the virtual console subsystem is
responsible.
The virtual consoles that are being spawned are responsible for 2
hotplug events for every console opened -- one on the opening of the
console, and one on the closing of the console.
If you run the tty2_test which opens and closes ttys (attached to this
email) you'll see THOUSANDS of hotplug events. After running for 1
minute on a 16p ia64 I had well over 4000 hotplug events.
If we're unlucky enough to fall below the low-water memory point at the
same time tty2_test is spawning, the OOM-killer starts up. Memory is
taken up by the hotplug events ... and we're off into the weeds.
The issue with the virtual console code is that it uses the class_simple
library. This is a problem as the library pre-defines a global kset
parent as class_obj (or at least AFAICT). This parent is used by ALL
subsystems using the class_simple, not just the virtual console subsystem.
This parent has a pointer to allow hotplug slot operations for all it's
children (including the virtual consoles). IMO zero-ing this pointer
out is not a valid option as this would break hotplug op's for many
other subystems.
** I did notice that the class struct has it's own hotplug value --
can/should this be used to override the parent's hotplug operations? **
P.
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next reply other threads:[~2005-03-30 16:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-30 16:30 Prarit Bhargava [this message]
2005-03-30 16:31 ` Virtual Console Hotplug Leads to OOM Prarit Bhargava
2005-04-01 0:17 ` Greg KH
2005-04-01 13:42 ` Prarit Bhargava
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