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 <mszer...@suse.cz>
Date: Sat Dec 13 00:59:42 2014 +0100
ovl: check whiteout while reading directory
Don't make a separate pass for checking whiteouts, since we can do it while
reading the upper directory.
This will make it easier to handle multiple layers.
Signed-off-by: Miklos Szeredi <mszer...@suse.cz>
It probably happens like this:
overlayfs does a readdir, in which jffs2 takes a lock.
>From within the readdir fill callback, it calls lookup_one_len, which
ends up back in jffs2 and tries to take the same lock again.
=> deadlock.
- Felix
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