[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] domU oom -> xvda1 read-only without any notice?
On Wed, Mar 31, 2010 at 09:45:01AM +0100, Keir Fraser wrote: > >> Blkback communicates this kind of info to blkfront via a node in xenstore > >> named 'info'. Bit 2 of this numeric field indicates if a virtual disc is > >> read-only. I think it's more likely that the domU has internally confused > >> itself, rather than being told to mount read-only by dom0 -- the flags get > >> probed when the virtual disc first appears, and I don't think would get > >> probed again after that anyway without a full disc hot-unplug/replug. > > > > OK, thanks, so is there any way I could examine xen-blkfront then? :) > > I looked around and only found funny bits like: > > > > % cat /sys/module/xen_blkfront/drivers/xen:vbd/vbd-51713/block/xvda1/ro > > 0 > > AFAIK that means that the read-only-ness is not being propagated up to domU > block layer by the xen_blockfront driver. I'm not sure exactly what other > possibilities there are, but if the kernel has been OOMing processes then > perhaps you're in a runlevel or mode, or even a kenrel bug, in which rootfs > is forced read-only for other reasons? There have been bugs around OOM in > the past, and really it's a kernel path that's obviously best avoided! Any > idea why the OOM occurred in the first place? Not really. It's prompted by a skipfish (web security scanner) run on the web server on the same machine, and that server has PHP that talks to the database. It does nicely for a few hours, then it bursts into flames. The 2.6.26 domU kernel reliably died completely in that situation, it's that SMP bug with the old forward-ported Xen patches. The new kernel survived some OOM situations, and obviously some others not so much :) This is the first time I saw it break blkfront, so I figured it may be useful to report early in case I can gather some more debug info now. If nobody has any immediate suggestions as to what to do, I'm going to restart it now because we need the machine in a not-so-useless state. But I'll probably reproduce the same problem tonight anyway. -- 2. That which causes joy or happiness. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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