On Fri, Feb 10, 2017 at 07:48:26PM -0500, Brian Wrenn wrote: > Hi, Hey Brian- > I have a kernel module running within Linaro 4.4.9 with PREEMPT RT 17. > Within that module I attempt to transfer data from the kernel module > to user space. The user space application does not run real-time, > just in plain Linux user space. With each attempted run I get a > kernel dump that begins with the following: > > Unable to handle kernel paging request at virtual address <some address> > > I'm using mmap in a fairly straightforward way. Basically, upon an > IOC command from the user space application to the kernel module, the > kernel module attempts to copy data into the memory mapped area. I've > checked, double checked, and triple checked that I'm not writing to a > bad address or an address outside of the mmap'ed area. How are you performing your checks? How are you performing the copy? > Are there some special (special in the sense of in addition to or > instead of the way done for a non-PREEMPT-RT kernel) things one must > do to safely write mmap'ed data within a PREEMPT RT kernel? You didn't explicitly mention it, so I thought I'd check: the same operation, performed on a non-RT kernel doesn't reproduce the above OOPs? Julia -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
