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

[Alexandre Demers <alexandre.f.demers@gmail.com>]

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;
>   }