Re: [OpenWrt-Devel] Device tree issues with TL-WDR4900 (mpc85xx) and kernel 4.0.1

[Felix Fietkau <nbd@openwrt.org>]

On 2015-06-15 10:20, Miklos Szeredi wrote:
> On Thu, Jun 11, 2015 at 2:01 PM, Miklos Szeredi <mszeredi@suse.cz> wrote:
>> On 7 May 2015 at 15:49, Felix Fietkau <nbd@openwrt.org> wrote:
>>> On 2015-05-07 08:01, Wojciech Dubowik wrote:
>>>> Try to boot with kernel locking enabled. I have seen jffs2 deadlocks on
>>>> readdir. As far as I remember
>>>> with this patch it went through but I don't know anymore whether I have
>>>> changed sth in config.
>>>>
>>>> Have a look at (search engine...) [PATCH] fs: jffs2: Add setup code for
>>>> spi nor flash.
>>>>
>>>> Even with this patch I got some possible dead lock warnings so it might
>>>> be just a partial cure. BTW it's
>>>> a bit scary for future use. Looks like jffs2 doesn't get enough care...
>>> I believe the locking issues are an overlayfs regression, maybe even
>>> the same one as this one (which I fixed years ago):
>>> http://linux-fsdevel.vger.kernel.narkive.com/XRtXLDlf/patch-1-2-overlayfs-fix-a-deadlock-in-ovl-dir-read-merged
>>>
>>> I believe this is the cause of the regression:
>>>
>>> commit 49c21e1cacd74a8c83407c70ad860c994e606e25
>>> Author: Miklos Szeredi <mszeredi@suse.cz>
>>> Date:   Sat Dec 13 00:59:42 2014 +0100
>>>
>>
>> I'm working on 4.0 support for ar71xx and found that
>> /etc/rc.d/S00sysfixtime is not able to finish it's job after second
>> boot after flashing (t.i. after overlayfs is switched to jffs). I've
>> run strace and found that find hangs on the very last getdents64 call
>> (before calling it succesfully many times on previous
>> files/directories).
>> I've reverted every change up to
>> 49c21e1cacd74a8c83407c70ad860c994e606e25 to overlayfs and it started
>> working. Applying 49c21e1cacd74a8c83407c70ad860c994e606e25 back breaks
>> it. So this commit is indeed the cause of regression.
>>
>> Miklos, any ideas how to fix it in current tree? I'm using 4.0.5 now
>> but AFAIK there were no more changes to overlayfs.
> 
> What's the full mount setup?  (cat /proc/mounts)
/dev/root /rom squashfs ro,relatime 0 0
proc /proc proc rw,noatime 0 0
sysfs /sys sysfs rw,noatime 0 0
tmpfs /tmp tmpfs rw,nosuid,nodev,noatime 0 0
/dev/mtdblock8 /overlay jffs2 rw,noatime 0 0
overlayfs:/overlay / overlay rw,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work 0 0
tmpfs /dev tmpfs rw,relatime,size=512k,mode=755 0 0
devpts /dev/pts devpts rw,relatime,mode=600 0 0
debugfs /sys/kernel/debug debugfs rw,noatime 0 0

- Felix