Hello, On Thu, Mar 07, 2013 at 02:47:48AM +0000, Ming Lei wrote: > Commit 14318efb(ARM: 7587/1: implement optimized percpu variable access) > introduces arm's __my_cpu_offset to optimize percpu vaiable access, > which really works well on hackbench test, but may cause __my_cpu_offset > to return garbage value before it is initialized in cpu_init() called > by setup_arch, so accessing a percpu variable before setup_arch may cause > kernel hang. But the generic__my_cpu_offset always returns zero before > percpu area is brought up. > > So the patch tries to clear __my_cpu_offset on boot CPU early > to avoid boot hang. > > At least now percpu variable is accessed by lockdep before > setup_arch(), and enabling CONFIG_LOCK_STAT or CONFIG_DEBUG_LOCKDEP > can trigger kernel hang.
For the record, can you include a backtrace or something please? The description makes it sounds like a caller bug, so it would be good to document a valid user of per-cpu before cpu_init(). Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
