From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Steven Rostedt In-Reply-To: References: Content-Type: text/plain; charset="ISO-8859-15" Date: Thu, 17 Mar 2011 10:08:56 -0400 Message-ID: <1300370936.16880.96.camel@gandalf.stny.rr.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Subject: Re: um: WARNING: at kernel/futex.c:786 __unqueue_futex To: richard -rw- weinberger Cc: laijs@cn.fujitsu.com, LKML , user-mode-linux-devel@lists.sourceforge.net, dvhart@linux.intel.com List-ID: On Thu, 2011-03-17 at 13:25 +0100, richard -rw- weinberger wrote: > Lai, > > Your commit 2e12978a > (futex,plist: Pass the real head of the priority list to plist_del()) > triggers gazillions warnings on User Mode Linux (x86, Linus' tree as of today): > > ------------[ cut here ]------------ > WARNING: at kernel/futex.c:786 __unqueue_futex+0x12/0x16() > Modules linked in: > 27d4cce8: [<081c13fe>] dump_stack+0x1c/0x20 > 27d4cd00: [<08071aa0>] warn_slowpath_common+0x49/0x5f > 27d4cd18: [<08071acb>] warn_slowpath_null+0x15/0x19 > 27d4cd28: [<0808fdb8>] __unqueue_futex+0x12/0x16 > 27d4cd38: [<0808fef3>] futex_wait+0x137/0x1ed > 27d4cdd0: [<080910c3>] do_futex+0x78/0x7c4 > 27d4cedc: [<080918e6>] sys_futex+0xd7/0xed > 27d4cf28: [<0805abf6>] handle_syscall+0x7a/0x98 > 27d4cf78: [<080685d9>] userspace+0x2c9/0x370 > 27d4cfe0: [<08058be5>] fork_handler+0x53/0x5b > 27d4cffc: [<00000000>] 0x0 > > ---[ end trace ed7709f235f82328 ]--- > > !spin_is_locked(q->lock_ptr) in the WARN_ON() at line 786 > triggers the warnings. Crap, I bet you are running CONFIG_SMP=n. I'll test this. We may need to make that a WARN_ON_SMP(). -- Steve > > I'm not sure whether this shows a bug within UML > or the WARN_ON() is wrong. > > What do you think? >