Date: Mon, 6 Mar 2006 14:24:42 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Rui Nuno Capela <rncbc@rncbc.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: realtime-preempt patch-2.6.15-rt18 issues
Message-ID: <20060306132442.GA12359@elte.hu>
References: <45924.195.245.190.93.1141647094.squirrel@www.rncbc.org>
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* Rui Nuno Capela <rncbc@rncbc.org> wrote:

> Hi, Ingo,
> 
> I think I would let you know that I'm still on 2.6.15-rt16, which 
> works great for the most purposes, on all of my boxes.
> 
> My problem is that the current/latest of the realtime-preempt patch, 
> 2.6.15-rt18, has some showstoppers, at least for my day-to-day usage.
> 
> First one, and I think this is a return of an old buglet. Its the one 
> that occurs every time an usb-storage device is unplugged (e.g. a usb 
> flash stick). Once that happens, the usb subsystem gets seriously 
> crippled.
> 
> Here goes a sample dmesg output of this occurrence (the complete listing
> is attached, as is the corresponding kernel .config).
> 
> ...
> usb 2-1: USB disconnect, address 2
> slab error in kmem_cache_destroy(): cache `scsi_cmd_cache': Can't free all
> objects

hm, this implicates the SLAB code. I've uploaded -rt19, does it work any 
better [there i've included a newer version of the rt-SLAB code]? If you 
still get the same problem even under -rt19, do things improve if you 
enable CONFIG_EMBEDDED and CONFIG_SLOB?

(-rt19 also has the tasklet/ALSA fix, and some other fixlets)

	Ingo
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