Am 16.08.2013 18:45, schrieb Tejun Heo: > Hello, > > On Fri, Aug 16, 2013 at 06:38:58PM +0200, Richard Weinberger wrote: >>> cc'ing uml people. Hey, guys, workqueue uses proble_kernel_read() to >>> print out workqueue related information during oops because those >>> events are completely asynchronous and workqueue states may not be >>> consistently accessible. It seems like uml doesn't implement >>> probe_kernel_read() and tries direct derference of incorrect pointers >>> leading to its own oops. Maybe uml should check whether the memory is >>> mapped from probe_kernel_read()? >> >> You are already talking to UML people. ;) > > Ooh... :) > >> Anyway, I'll investigate into that. >> What I see so far is that pwq is NULL after probe_kernel_read(). > > Yeah, and that should be fine. &pwq->wq would be just an offset of wq
Yep. Now my brain also parsed the C notation correctly. Sorry for the completely wrong patch. > from NULL which is an invalid pointer but probe_kernel_read() should > be able to handle that and probably just return 0 or -1 (all bits > set). I *think* what's necessary is making probe_kernel_read() use > mincore() to fine out whether the requested address is mapped (it > should return -EFAULT if not) and try to dereference the address iff > it's mapped. UML needs a custom probe_kernel_read()? Fine. :) Thanks, //richard ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
