On Donnerstag, 13. August 2009, Mel Gorman wrote: > On Wed, Aug 12, 2009 at 02:40:30PM -0400, Arnaud Faucher wrote: > > I have a rather similar problem on a driver that I try to keep > > up-to-date with recent kernel versions > > (http://code.ximeta.com/trac-ndas/ticket/1110#comment:30). The NDAS > > hardware is an ethernet-enabled disk controller on one chip, kind of a > > cheap iSCSI. > > > > In my case there is no oops: the symptoms are that the read blocks seem > > to be swapped or full of garbage. > > > > After investigation in the NDAS code, the bug triggers when the driver > > tries to merge adjacent requests before sending them to the controller. > > I had to disable this merge in order to restore normal behavior, at the > > expense of a reduced efficiency. > > That is a very interesting point and one I hadn't considered. The point > of the patch was to help drivers that merge adjacent requests if they > happen to be physically contiguous. The reported bug that led to the > patch was a regression of memory not being physically contiguous and > requests not being merged. > > > > After this oops, system startup continues. Then the next oops occurs: > > > > > > This one is new, since I try to mount the connected SD card. > > > > Mel's buffer overrun theory seems to apply in the NDAS driver case, > > where the original requests adjacency test seems faulty. > > > > May it also be the cause of the SD mounting crash ? > > It's a possibility. If it's not an overrun, it's possible that the > automatic merging code is buggy as well. > > Juergen, is the disk controller on your machine capable of merging > requests? If so, can you disable it and see if the bug still occurs > please? Hmmm, hard to say. Maybe the author of this driver can say more. @Ben: MMC/SD/SDHC driver for the s3c2440-CPU. Can you answer Mel's question? Regards, Juergen -- Pengutronix e.K. | Juergen Beisert | Linux Solutions for Science and Industry | Phone: +49-8766-939 228 | Vertretung Sued/Muenchen, Germany | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
