On Wed, 23 Jul 2014, Linus Torvalds wrote: > > Well, it looks like we f*cked up something after -rc5 since I'm starting > > to see lockdep splats all over the place which I didn't see before. I'm > > running rc6 + tip/master. > > > > There was one in r8169 yesterday: > > > > https://lkml.kernel.org/r/20140722081840.GA6462@xxxxxxx > > > > and now I'm seeing the following in a kvm guest. I'm adding some more > > lists to CC which look like might be related, judging from the stack > > traces. > > Hmm. I'm not seeing the reason for this. > > > [ 31.704282] [ INFO: possible irq lock inversion dependency detected ] > > [ 31.704282] 3.16.0-rc6+ #1 Not tainted > > [ 31.704282] --------------------------------------------------------- > > [ 31.704282] Xorg/3484 just changed the state of lock: > > [ 31.704282] (tasklist_lock){.?.+..}, at: [<ffffffff81184b19>] send_sigio+0x59/0x1b0 > > [ 31.704282] but this lock took another, HARDIRQ-unsafe lock in the past: > > [ 31.704282] (&(&p->alloc_lock)->rlock){+.+...} > > Ok, so the claim is that there's a 'p->alloc_lock' (ie "task_lock()") > that is inside the tasklist_lock, which would indeed be wrong. But I'm > not seeing it. The "shortest dependencies" thing seems to imply > __set_task_comm(), but that only takes task_lock. > It's the reverse, task_lock() inside tasklist_lock is fine but it's complaining about taking tasklist_lock inside task_lock(). I don't think it's anything that's sitting in tip/master nor is it something that was introduced during this merge window. I think this has been the behavior dating back to commit 94dfd7edfd5c ("USB: HCD: support giveback of URB in tasklet context"). -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
