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Re: [Xen-devel] Problems with dom0 and low memory

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Problems with dom0 and low memory
From: Jérôme Petazzoni <jp@xxxxxxxx>
Date: Tue, 07 Dec 2004 22:47:55 +0100
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If under tight memory conditions you get errors from the blkdev layer
in DOM0 then the backend driver will simply send those erros back to
the frontend, which will pass the error up into xenU's blkdev layer.
What ext3 then does with that error is not really Xen's problem -- a
similar low-memory condition running directly on the hardware (i.e.,
without Xen)  would likely have the same outcome.

I totally agree. But dom0 should rather display a nice "blkdev backend driver ran out of memory" instead of this ugly stack dump.

Unless the problem comes from Linux code, and is forwarded by Xen "as-is", since Xen itself doesn't now more details about it ?

Also, it would be nice to be able to select between the following behaviours when such an error occurs :
- abort the block device totally (the error gets noticed at once)
- switch the block device to read-only to prevent further corruption
- continue operation (like now)

This would be philosophically equivalent to the "errors=panic/continue/remount-to" behaviours ...


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