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Date: Mon, 23 Sep 2013 13:41:29 -0400
From: "J. Bruce Fields" <bfields@fieldses.org>
To: Toralf =?utf-8?Q?F=C3=B6rster?= <toralf.foerster@gmx.de>
Cc: Jan Kara <jack@suse.cz>,
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        Linux Kernel <linux-kernel@vger.kernel.org>,
        "J. Bruce Fields" <bfields@redhat.com>
Subject: Re: Issues with a rather unusual configured NFS server
Message-ID: <20130923174129.GA19720@fieldses.org>
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On Sun, Sep 22, 2013 at 06:58:29PM +0200, Toralf Förster wrote:
> On 09/10/2013 04:09 PM, J. Bruce Fields wrote:
> > On Sat, Sep 07, 2013 at 10:44:00PM +0200, Toralf Förster 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.
> > 
> > This is a slightly different test case, so for now it sounds like this
> > could be a preexisting problem, not a regression?
> > 
> Yes, pre-existing. I'm trying to bisect it, the issue is already in 7d3107d.
> 
> But every attempt to get the first bad commit before that commit id
> failed till now. I started many attempts between v3.10 and 7d3107d. I
> could not reproduce that issue 100% in that interval. In that interval
> either all tested commits doesn't show the issue or the NFS client hangs
> during the stop of NFS service infinitely - and counting that as a "bad"
> commit doesn't work.
> 
> FWIW a single test case currently takes 2 1/2 hour and even then I do
> not fully trust the result  (except for a bad commit, that's clear.

Well, we should figure out some other way to narrow down the problem....

I was trying to at least work out where exactly this crash was, but I
don't have a commit 768c9d3.

--b.

> 
> 
> > --b.
> > 
> >>
> >> 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
> >> #10 0x08113948 in shrink_dcache_for_umount (sb=0x463b8000) at fs/dcache.c:1002
> >> #11 0x08101677 in generic_shutdown_super (sb=0x463b8000) at fs/super.c:404
> >> #12 0x08102395 in kill_anon_super (sb=0x0) at fs/super.c:875
> >> #13 0x081d3ff8 in nfs_kill_super (s=0x0) at fs/nfs/super.c:2598
> >> #14 0x0810153a in deactivate_locked_super (s=0x463b8000) at fs/super.c:294
> >> #15 0x081015d1 in deactivate_super (s=0x463b8000) at fs/super.c:319
> >> #16 0x08119c0c in mntfree (mnt=<optimized out>) at fs/namespace.c:891
> >> #17 mntput_no_expire (mnt=0x0) at fs/namespace.c:929
> >> #18 0x0811b195 in SYSC_umount (flags=<optimized out>, name=<optimized out>) at fs/namespace.c:1335
> >> #19 SyS_umount (name=134633856, flags=2) at fs/namespace.c:1305
> >> #20 0x080618e2 in handle_syscall (r=0x498be5d4) at arch/um/kernel/skas/syscall.c:35
> >> #21 0x08073c0d in handle_trap (local_using_sysemu=<optimized out>, regs=<optimized out>, pid=<optimized out>) at arch/um/os-Linux/skas/process.c:198
> >> #22 userspace (regs=0x498be5d4) at arch/um/os-Linux/skas/process.c:431
> >> #23 0x0805e65c in fork_handler () at arch/um/kernel/process.c:160
> >> #24 0x00000000 in ?? ()
> >>
> >>
> >>
> >> -- 
> >> MfG/Sincerely
> >> Toralf Förster
> >> pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3
> > 
> 
> 
> -- 
> MfG/Sincerely
> Toralf Förster
> pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3
> --
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