Re: 100% system time hang with git f2fs

[Marc Lehmann <schmorp@schmorp.de>]

On Fri, Oct 02, 2015 at 09:51:24AM -0700, Jaegeuk Kim <jaegeuk@kernel.org> wrote:
> > However, I have a freeze. When I mount the volume, start a du on it, and after
> > a while do:
> 
> How was your scenario?
> Did you delete device before, or just plain mount and umount?

After writing >2TB to it, I let it idle/gc for a while, then unmounted. Then
did a fsck and mount, and let it idle for the night. On the next day, I did a
du for a speed test, relaised I hadn't dropped the caches, interrupted the
du, and then trie drop_caches with the result.

> This should be shrinker is stuck on mutex. I suspect a deadlock.
> Can you do this, if you meet this again?

Will do. Btw, I already mentioned that /proc/*/stack didn't give a useful
backtrace. Since it was apparently running, I thought maybe run cat
/.../stack in a loop, and indeed, after a minute, I got one backtrace out
of it (the process doing the echo):

http://ue.tst.eu/2562aec1c51d4bad3d7b8b83380956a7.txt

Maybe that is already useful? It indeed mentions the shrinker.

(I did this after my mail, so didn't include it).

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