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Date:   Thu, 15 Nov 2018 12:45:04 -0500
From:   Sasha Levin <sashal@kernel.org>
To:     Minchan Kim <minchan@kernel.org>
Cc:     stable@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Hannes Reinecke <hare@suse.com>,
        Howard Chen <howardsoc@google.com>
Subject: Re: [PATCH] zram: close udev startup race condition as default groups
Message-ID: <20181115174504.GJ95254@sasha-vm>
References: <20181114055223.66476-1-minchan@kernel.org>
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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@gmail.com>
>Cc: Hannes Reinecke <hare@suse.com>
>Tested-by: Howard Chen <howardsoc@google.com>
>Signed-off-by: Minchan Kim <minchan@kernel.org>

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

--
Thanks,
Sasha