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Date: Sat, 7 Sep 2013 22:51:07 +0200
Message-ID: <CAFLxGvzGLYYmrHHZ+cLehp5x9gt3MFOMzgF26C-=PxtSoXhWTg@mail.gmail.com>
Subject: Re: [uml-devel] Issues with a rather unusual configured NFS server
From: richard -rw- weinberger <richard.weinberger@gmail.com>
To: =?ISO-8859-1?Q?Toralf_F=F6rster?= <toralf.foerster@gmx.de>
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
        Linux NFS mailing list <linux-nfs@vger.kernel.org>,
        "J. Bruce Fields" <bfields@redhat.com>,
        "user-mode-linux-devel@lists.sourceforge.net"
	<user-mode-linux-devel@lists.sourceforge.net>,
        Linux Kernel <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>,
        linux-ext4@vger.kernel.org
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On Sat, Sep 7, 2013 at 10:44 PM, Toralf F?rster <toralf.foerster@gmx.de> wrote:
> Today I run latest git tree with a patched UML (this patch + one for xterm issues) and got 2 times a core dump
> when I fuzzy test an UML machine with a nearly identical scenario as already described but just shutdowned
> both UML images instead of shooting one of it in the head.
>
> I'll probably need time to figure out a test case, but just as a pre-info here's the back trace:
>
> tfoerste@n22 ~ $ gdb --core=/mnt/ramdisk/core /usr/local/bin/linux-v3.11-7550-g768c9d3 -n -batch -ex bt
>
> warning: core file may not match specified executable file.
> [New LWP 7470]
> [New LWP 7479]
> [New LWP 7477]
> [New LWP 7478]
> Core was generated by `/usr/local/bin/linux-v3.11-7550-g768c9d3 earlyprintk ubda=/home/tfoerste/virtua'.
> Program terminated with signal 6, Aborted.
> #0  0xb77be424 in __kernel_vsyscall ()
> #0  0xb77be424 in __kernel_vsyscall ()
> #1  0x083aada5 in kill ()
> #2  0x0807163d in uml_abort () at arch/um/os-Linux/util.c:93
> #3  0x08071925 in os_dump_core () at arch/um/os-Linux/util.c:138
> #4  0x080613a7 in panic_exit (self=0x85b1518 <panic_exit_notifier>, unused1=0, unused2=0x85e76e0 <buf.15920>) at arch/um/kernel/um_arch.c:240
> #5  0x0809a398 in notifier_call_chain (nl=0x0, val=0, v=0x85e76e0 <buf.15920>, nr_to_call=-2, nr_calls=0x0) at kernel/notifier.c:93
> #6  0x0809a4e3 in __atomic_notifier_call_chain (nr_calls=<optimized out>, nr_to_call=<optimized out>, v=<optimized out>, val=<optimized out>, nh=<optimized out>) at kernel/notifier.c:182
> #7  atomic_notifier_call_chain (nh=0x85e76c4 <panic_notifier_list>, val=0, v=0x85e76e0 <buf.15920>) at kernel/notifier.c:191
> #8  0x08408628 in panic (fmt=0x0) at kernel/panic.c:128
> #9  0x081131c9 in shrink_dcache_for_umount_subtree (dentry=0x428028f0) at fs/dcache.c:941

That is:
                        if (dentry->d_lockref.count != 0) {
                                printk(KERN_ERR
                                       "BUG: Dentry %p{i=%lx,n=%s}"
                                       " still in use (%d)"
                                       " [unmount of %s %s]\n",
                                       dentry,
                                       dentry->d_inode ?
                                       dentry->d_inode->i_ino : 0UL,
                                       dentry->d_name.name,
                                       dentry->d_lockref.count,
                                       dentry->d_sb->s_type->name,
                                       dentry->d_sb->s_id);
                                BUG();
                        }

Do you also have the console output?

-- 
Thanks,
//richard