Messages in this thread | | | Date | Tue, 22 Dec 2009 15:50:31 +0800 | Subject | Re: 2.6.33-rc1 unusable due to scheduler issues, circular locking, WARNs and BUGs | From | Américo Wang <> |
| |
On Tue, Dec 22, 2009 at 3:41 PM, Xiaotian Feng <xtfeng@gmail.com> wrote: > On Tue, Dec 22, 2009 at 3:19 PM, Américo Wang <xiyou.wangcong@gmail.com> wrote: >> [Fix top-posting] >> >> On Tue, Dec 22, 2009 at 1:42 PM, Xiaotian Feng <xtfeng@gmail.com> wrote: >>> >>> On Tue, Dec 22, 2009 at 8:17 AM, Eric Paris <eparis@redhat.com> wrote: >>>> Trying to build a kernel on a 48 core x86_64 box using make -j 64 and >>>> I'm exploding in the scheduler. I'm running (and building) kernel >>>> f7b84a6ba7eaeba4e1df8feddca1473a7db369a5 There are three distinct >>>> signatures of problems. Some boots I'll see all 3 of these failures >>>> sometimes only 1 or 2 of them. That's the reason they are kinda split >>>> up in dmesg. >>>> >>>> 1) gcc/3141 is trying to acquire lock: >>>> (&(&sem->wait_lock)->rlock){......}, at: [<ffffffff81223234>] __down_read_trylock+0x13/0x46 >>>> >>>> but task is already holding lock: >>>> (&rq->lock){-.-.-.}, at: [<ffffffff8103dd2d>] task_rq_lock+0x51/0x83 >>>> >>>> 2) WARN() in kernel/sched_fair.c:1001 hrtick_start_fair() >>>> >>>> 3) NULL pointer dereference at 0000000000000168 in check_preempt_wakeup >>>> kernel/sched_fair.c >>>> >>>> Full backtraces are in the attached dmesg. >>>> >>> Does a revert of cd29fe6f2637cc2ccbda5ac65f5332d6bf5fa3c6 fix this problem? >> >> >> I don't think so... >> >> I think the most suspicious commit here is ab19cb23. It kicked >> "local_irq_save()" >> out, which means if the task is selected to run on another cpu which doesn't >> disable irq, we will have a page fault, thun we will try to hold mm->mmap_sem >> while we are holding rq->lock already. > > The page fault is from kernel NULL pointer deref. You should connect > the lockdep warning and kernel BUG together. >
Interesting.
1) Doesn't this NULL ptr def expose that we have a potential problem?
2) For NULL ptr def problem, commit 3a7e73a2e2 seems more suspicious.. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |