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Subject: Re: ubifs: assertion fails
From: Artem Bityutskiy <dedekind1@gmail.com>
To: Tanya Brokhman <tlinder@codeaurora.org>
Date: Mon, 07 Apr 2014 14:43:36 +0300
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On Tue, 2014-04-01 at 08:52 +0300, Tanya Brokhman wrote:
> The log isn't flooded with the above mentioned error, but it does repeat 
> several times.

Even though you do a lot of I/O operations?

If the accounting becomes incorrect, I think you'd see a warning for
each and every I/O operations.

Also, do you have several UBIFS file-systems mounted?

> Is there any way we can help in debugging and fixing this? Also, we're 
> running on a 3.10 based kernel and I saw a lot of patches that change 
> the shrinker after 3.10 on linux-next. What kernel version did you see 
> the shrinker errors on?

Well, you just need to stress the shrinker. I did it by simply adding a
hack to ubifs module init which kmalloc()'ed a lot of memory. Not
too-much, but enough to cause some pressure when doing a lot of I/O
operations and get UBIFS shrinker be invoked. This took me some amount
of time to get a good hack. I use a normal PC with some Fedora, and
nandsime. This makes it a lot easier to debug, comparing with doing this
on a real target. After all, shrinker is a generic component. I think
that PC had 4GB of RAM. I do not remember how much I allocated in my
hack.

I think I used older version than 3.10 back then.

-- 
Best Regards,
Artem Bityutskiy