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

Roman Yeryomin leroi.lists at gmail.com
Mon Jun 15 11:11:05 EDT 2015


On 15 June 2015 at 15:52, Miklos Szeredi <miklos at szeredi.hu> wrote:
> On Mon, Jun 15, 2015 at 10:24:28AM +0200, Felix Fietkau wrote:
>> On 2015-06-15 10:20, Miklos Szeredi wrote:
>> > On Thu, Jun 11, 2015 at 2:01 PM, Miklos Szeredi <mszeredi at suse.cz> wrote:
>> >> On 7 May 2015 at 15:49, Felix Fietkau <nbd at 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 at 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
>
>
> Following patch should fix the locking issue.
>
> Please test.
>

It worked! Thanks Miklos!
Felix, attaching tested and ready to commit patch.
Or do you want me to send it separately to the list?

Regards,
Roman
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