Re: [PATCH] zram: close udev startup race condition as default groups

[Sasha Levin]

On Wed, Nov 14, 2018 at 02:52:23PM +0900, Minchan Kim wrote:
> commit fef912bf860e upstream.
> commit 98af4d4df889 upstream.
>
> I got a report from Howard Chen that he saw zram and sysfs race(ie,
> zram block device file is created but sysfs for it isn't yet)
> when he tried to create new zram devices via hotadd knob.
>
> v4.20 kernel fixes it by [1, 2] but it's too large size to merge
> into -stable so this patch fixes the problem by registering defualt
> group by Greg KH's approach[3].
>
> This patch should be applied to every stable tree [3.16+] currently
> existing from kernel.org because the problem was introduced at 2.6.37
> by [4].
>
> [1] fef912bf860e, block: genhd: add 'groups' argument to device_add_disk
> [2] 98af4d4df889, zram: register default groups with device_add_disk()
> [3] http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/
> [4] 33863c21e69e9, Staging: zram: Replace ioctls with sysfs interface
>
> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxxx>
> Tested-by: Howard Chen <howardsoc@xxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>

I've queued this for 4.19 and 4.18, but it doesn't apply to anything
older than that.

--
Thanks,
Sasha