Re: [PATCH v6 00/99] XArray version 6

[Matthew Wilcox]

On Thu, Jan 18, 2018 at 05:07:50PM +0100, David Sterba wrote:
> On Wed, Jan 17, 2018 at 12:20:24PM -0800, Matthew Wilcox wrote:
> > From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> > 
> > This version of the XArray has no known bugs.
> 
> I've booted this patchset on 2 boxes, both had random problems during
> boot. On one I was not able to diagnose what went wrong. On the other
> one the system booted up to userspace and failed to set up networking.
> Serial console worked and the network service complained about wrong
> format of /usr/share/wicked/schema/team.xml . That's supposed to be a
> text file, though hexdump showed me lots of zeros. Trimmed output:
> 
> 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> (similar output here)
> *
> 00000a10  00 00 00 00 00 00 00 00  11 03 00 00 00 00 00 00  |................|
> 00000a20  20 8b 7f 01 00 00 00 00  a0 84 7d 01 00 00 00 00  | .........}.....|
> 00000a30  00 00 00 00 00 00 00 00  10 89 7f 01 00 00 00 00  |................|
> 00000a40  a0 84 7d 01 00 00 00 00  00 00 00 00 00 00 00 00  |..}.............|
> 00000a50  80 8a 7f 01 00 00 00 00  e0 cf 7d 01 00 00 00 00  |..........}.....|
> 00000a60  00 00 00 00 00 00 00 00  60 8a 7f 01 00 00 00 00  |........`.......|
> 00000a70  a0 84 7d 01 00 00 00 00  00 00 00 00 00 00 00 00  |..}.............|
> 00000a80  30 89 7f 01 00 00 00 00  a0 84 7d 01 00 00 00 00  |0.........}.....|
> 00000a90  00 00 00 00 00 00 00 00  60 f2 7f 01 00 00 00 00  |........`.......|
> 00000aa0  40 fd 7e 01 00 00 00 00  00 00 00 00 00 00 00 00  |@.~.............|
> 00000ab0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 00001000  3e 0a 20 20 3c 2f 6d 65  74 68 6f 64 3e 0a 3c 2f  |>.  </method>.</|
> 00001010  73 65 72 76 69 63 65 3e  0a                       |service>.|
> 
> There's something at the end of the file that does look like a xml fragment.
> The file size is 4121. This looks to me like exactly the first page of the file
> was not read correctly.
> 
> The xml file is supposed to be read-only during startup, so there was no write
> in flight. 'rpm -Vv' reported only this file corrupted. Booting to other
> kernels was fine, network up, and the file was ok again. So the
> corruption happened only in memory, which leads me to conclusion that
> there is an unknown bug in your patchset.

Thank you!  I shall attempt to debug.  Was this with a btrfs root
filesystem?  I'm most suspicious of those patches right now, since they've
received next to no testing.  I'm going to put together a smaller patchset
which just does the page cache conversion and nothing else in the hope
that we can get that merged this year.