linux-kernel - Re: Issues with a rather unusual configured NFS server

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Message-ID: <523F21B5.2050305@gmx.de>
Date:	Sun, 22 Sep 2013 18:58:29 +0200
From:	Toralf Förster <toralf.foerster@....de>
To:	"J. Bruce Fields" <bfields@...ldses.org>
CC:	Jan Kara <jack@...e.cz>,
	Linux NFS mailing list <linux-nfs@...r.kernel.org>,
	"user-mode-linux-devel@...ts.sourceforge.net" 
	<user-mode-linux-devel@...ts.sourceforge.net>,
	linux-ext4@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	"J. Bruce Fields" <bfields@...hat.com>
Subject: Re: Issues with a rather unusual configured NFS server

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.


> --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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