Re: [Regression, bisected 9e30cc] "sysfs, kernfs: no need to kern_mount() sysfs from sysfs_init()" prevents system from booting correctly

From: Alexandre Demers
Date: Sat Mar 29 2014 - 18:09:30 EST


That fixes the problem, I'm now running 3.14-rc8 with your patch applied.

Alexandre Demers

On Sat 29 Mar 2014 02:12:58 PM EDT, Tejun Heo wrote:
Hello, Alexander.

On Thu, Mar 27, 2014 at 01:47:53PM -0400, Alexandre Demers wrote:
I'll do my best, but I just don't have enough time right now for
everything I have to do at home and dig this bug. I may be able to
look at it in the next couple of days though, or it may go somewhere
next week... That being said, I tried yesterday to have a better idea
and I thank you for the "ScrLck" trick, I didn't know that it was
working. Nevertheless I didn't find anything.

It seems as if the transition from the temporary kernel's fs to the
hard disk's fs is not done correctly. If I boot with a working kernel
after that, I can't find any trace of where it was trying to copy the
files or of any partition being full. Could it be filling the RAM
until it reaches its maximum capacity (16GB to fill before hitting the
limit and throwing the errors)? That would explain at least why it
takes so much time before the flood of errors begins...

That could definitely be the case. I'd really like to get to the
bottom of it. It's really curious that there aren't more people
reporting the same problem. Can you please try whether the following
patch makes the regression go away?

Thanks!

diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index a66ad61..a3223e2 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -75,5 +75,7 @@ int __init sysfs_init(void)
return err;
}

+ WARN_ON(IS_ERR(kern_mount(&sysfs_fs_type)));
+
return 0;
}
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