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Date:      Sun, 17 May 2015 21:26:23 +0200
From:      "Ronald Klop" <ronald-lists@klop.ws>
To:        freebsd-arm@freebsd.org
Subject:   Re: Random Kernel Panic on Dreamplug (FS related)
Message-ID:  <op.xysn99y5kndu52@ronaldradial.radialsg.local>
In-Reply-To: <1431814583.91685.39.camel@freebsd.org>
References:  <542559BC.7090100@gmail.com> <20140929040126.GG43300@funkthat.com> <54291B74.5010307@gmail.com> <20140930112937.GU43300@funkthat.com> <542A9EA4.70109@gmail.com> <20140930123010.GZ43300@funkthat.com> <542AB897.3020309@gmail.com> <1412086795.66615.363.camel@revolution.hippie.lan> <542ABE45.3020402@gmail.com> <1431814583.91685.39.camel@freebsd.org>

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On Sun, 17 May 2015 00:16:23 +0200, Ian Lepore <ian@freebsd.org> wrote:

> On Tue, 2014-09-30 at 16:29 +0200, Mattia Rossi wrote:
>> Am 30.09.2014 16:19, schrieb Ian Lepore:
>> > On Tue, 2014-09-30 at 16:05 +0200, Mattia Rossi wrote:
>> >> Am 30.09.2014 14:30, schrieb John-Mark Gurney:
>> >>> Mattia Rossi wrote this message on Tue, Sep 30, 2014 at 14:14 +0200:
>> >>>> Am 30.09.2014 13:29, schrieb John-Mark Gurney:
>> >>>>> Mattia Rossi wrote this message on Mon, Sep 29, 2014 at 10:42  
>> +0200:
>> >>>>>> Am 29.09.2014 06:01, schrieb John-Mark Gurney:
>> >>>>>>> Mattia Rossi wrote this message on Fri, Sep 26, 2014 at 14:19  
>> +0200:
>> >>>>>>>> This might be part of the weird FFS issues the Dreamplug has  
>> and no-one
>> >>>>>>>> knows why they're happening.
>> >>>>>>> Are you running w/ FFS journaling?  If so, try turning it off,  
>> but
>> >>>>>>> keeping softupdates on..
>> >>>>>> No journaling, no softupdates. I'll try enabling softupdates  
>> next time.
>> >>>>>> don't know if it will panic though
>> >>>>>>>> data_abort_handler() at data_abort_handler+0x5c0
>> >>>>>>>>            pc = 0xc0de7a28  lr = 0xc0dd711c (exception_exit)
>> >>>>>>>>            sp = 0xde019898  fp = 0xde019a20
>> >>>>>>>>            r4 = 0xffffffff  r5 = 0xffff1004
>> >>>>>>>>            r6 = 0xc3f3f6c0  r7 = 0x00001000
>> >>>>>>>>            r8 = 0xc443e880  r9 = 0x00000000
>> >>>>>>>>           r10 = 0xc3d69000
>> >>>>>>>> exception_exit() at exception_exit
>> >>>>>>>>            pc = 0xc0dd711c  lr = 0xc0d53828  
>> (ffs_truncate+0xaa8)
>> >>>>>>>>            sp = 0xde0198e8  fp = 0xde019a20
>> >>>>>>>>            r0 = 0xd0238120  r1 = 0x00000e60
>> >>>>>>>>            r2 = 0x00000000  r3 = 0x00000000
>> >>>>>>>>            r4 = 0x00000120  r5 = 0x00000000
>> >>>>>>>>            r6 = 0xc3f3f6c0  r7 = 0x00001000
>> >>>>>>>>            r8 = 0xc443e880  r9 = 0x00000000
>> >>>>>>>>           r10 = 0xc3d69000 r12 = 0xd0238120
>> >>>>>>>> memset() at memset+0x48
>> >>>>>>>>            pc = 0xc0de521c  lr = 0xc0d53828  
>> (ffs_truncate+0xaa8)
>> >>>>>>>>            sp = 0xde0198e8  fp = 0xde019a20
>> >>>>>>>> Unwind failure (no registers changed)
>> >>>>>>> No more beyond this?   If you could run addr2line on 0xc0d53828  
>> so
>> >>>>>>> that we know where in ffs_truncate it's failing, that'd be very
>> >>>>>>> nice...
>> >>>>>> So I was trying to save the coredump in  order to reboot and run
>> >>>>>> addr2line, but that failed:
>> >>>>>>
>> >>>>>> Physical memory: 504 MB
>> >>>>>> Dumping 67 MB:(da0:umass-sim0:0:0:0): WRITE(10). CDB: 2a 00 01  
>> d5 1f20
>> >>>>>> 00 00 01 00  <sip:2000000100>
>> >>>>>> (da0:umass-sim0:0:0:0): CAM status: Resource Unavailable
>> >>>>>> (da0:umass-sim0:0:0:0): Error 5, Retries exhausted
>> >>>>>> Aborting dump due to I/O error.
>> >>>>>>
>> >>>>>> ** DUMP FAILED (ERROR 5) **
>> >>>>>>
>> >>>>>> So I guess this error is related to the CAM errors I'm getting  
>> from time
>> >>>>>> to time. I was hoping that those errors were related to the  
>> INVARIANTS
>> >>>>>> option that slowed down the system and thus might have triggered  
>> CAM
>> >>>>>> errors, but obviously the SD Card seems to be the real issue  
>> here.
>> >>>>>> So no crashdump for further analysis.
>> >>>>> That's fine.. w/ the addr2line we have some lines to explore...
>> >>>>>
>> >>>>>> Interestingly the CAM errors didn't show up on the terminal as  
>> other
>> >>>>>> times, the kernel just panicked straight away.
>> >>>>> Hmm.. that is odd.. someone who knows the SD card layer should  
>> look
>> >>>>> at this part...  It could be that the SD card driver doesn't  
>> handle
>> >>>>> dumping (there is this global flag that gets set) properly and  
>> the driver
>> >>>>> needs to behave differently when it's set...
>> >>>> I also need to grab a new SD card, just to make sure it's really  
>> not the
>> >>>> card.
>> >>>>
>> >>>>>> But I've got the addr2line output, even though I'm not sure it  
>> makes any
>> >>>>>> difference:
>> >>>>>>
>> >>>>>> addr2line -f -e /mnt/kernel.debug 0xc0d53828
>> >>>>>>
>> >>>>>> ffs_truncate
>> >>>>>> /usr/devel/dreamplug/sys/ufs/ffs/ffs_inode.c:321
>> >>>>> can you give me the contents of the line?  and a few lines of  
>> context
>> >>>>> around it?   In HEAD's source, this is DOINGASYNC, and there is  
>> no call
>> >>>>> to memset, nor a variable assignment that would result in memset  
>> being
>> >>>>> called...
>> >>>> Same here.. The file hasn't been changed in a while (Fri, 31 May  
>> 2013):
>> >>>>
>> >>>>                   ip->i_size = length;
>> >>>>                   DIP_SET(ip, i_size, length);
>> >>>>                   if (bp->b_bufsize == fs->fs_bsize)
>> >>>>                           bp->b_flags |= B_CLUSTEROK;
>> >>>>                   if (flags & IO_SYNC)
>> >>>>                           bwrite(bp);
>> >>>> 321:        else if (DOINGASYNC(vp))
>> >>>>                           bdwrite(bp);
>> >>>>                   else
>> >>>>                           bawrite(bp);
>> >>>>                   ip->i_flag |= IN_CHANGE | IN_UPDATE;
>> >>>>                   return (ffs_update(vp, !DOINGASYNC(vp)));
>> >>>>
>> >>>> No idea what's going on.
>> >>> ok, could you send me the output of objdump -dSl, but you only need
>> >>> to include the part from XXXXX <ffs_truncate>: to the next  
>> XXX<func>:
>> >>> line...  probably off list as it'll be quite long...
>> >> I'm sorry, but given that I just broke all my working worlds using  
>> fsck,
>> >> I'm not going to be able to do that until I'm back from holidays....
>> >> currently working on the stuff remotely and after today's work day,  
>> I'm
>> >> not going to be able to get my hands on the dreamplug.
>> >>
>> >>
>> > BTW, for anyone playing with this problem, step one is to edit
>> > your /etc/fstab and set the fsck pass number to 0 for all filesystems.
>> > There's a risk of filesystem corruption after a crash, but it's  
>> smaller
>> > than the 100% corruption rate of letting fsck run. :)
>> >
>> Of course! Great idea :-) Sometimes just can't think of the right tweak
>> to save a lot of pain...
>>
>> Anyhow, I just found out, that I was rebooting the dreamplug from the sd
>> card instead of the usb stick the whole time, and the usb stick hasn't
>> been damaged enough by fsck, so it actually booted :-) I'll send the
>> objdump soon.
>
> A (very) late update on this.... It looks like we may have tracked the
> change that started all this down to the introduction of unmapped IO,
> almost 2 years ago now.  I still can't find the root cause, but I think
> disabling unmapped IO on armv4/5 is a viable workaround, which Warner
> committed this morning as r283014.
>
> --Ian


This sounds promising for the use of my Sheevaplugs.
I will try this soon. Thanks.

Ronald.



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