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From: DX Cui <rijcos@gmail.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: linux-mm@kvack.org,
	Matt Tolentino <matthew.e.tolentino@intel.com>,
	Dave Hansen <haveblue@us.ibm.com>, Andrew Morton <akpm@osdl.org>,
	Linus Torvalds <torvalds@osdl.org>,
	Nathan Fontenot <nfont@linux.vnet.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: memory hot-add: the kernel can notify udev daemon before creating the sys file state?
Date: Thu, 29 May 2014 16:48:22 +0800	[thread overview]
Message-ID: <CAJm7N87BNiuNkqrU+EeeejXXp_aOH+jVh-kyZr890Aedg__Ftg@mail.gmail.com> (raw)
In-Reply-To: <53864B65.8080705@intel.com>

On Thu, May 29, 2014 at 4:47 AM, Dave Hansen <dave.hansen@intel.com> wrote:
> On 05/23/2014 05:27 AM, DX Cui wrote:
>> It looks the new "register_memory() --> ... -> device_add()" path has the
>> correct order for sysfs creation and notification udev.
>>
>> It would be great if you can confirm my analysis. :-)
>
> Your analysis looks correct to me.  Nathan's patch does, indeed look
> like a quite acceptable fix.  How far back do those sysfs attribute
> groups go, btw?

I'm not familiar with it.
My gut feeling is: this may need non-trivial efforts -- probably several
extra patches need to be backported too.

BTW, this race condition finally can cause kernel panic when old Linux
VMs of kernel versions <3.9.x, like CentOS 6.5, run on Hyper-V, AND
memory hot-add and the balloon driver are used:

https://bugzilla.redhat.com/show_bug.cgi?id=1102551
(there is a workaround patch for ***CentOS6.5*** in the bug entry)

-- DX

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      reply	other threads:[~2014-05-29  8:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-05-23  9:46 DX Cui
2014-05-23 12:27 ` DX Cui
2014-05-25 15:41   ` DX Cui
2014-05-28 20:32     ` Nathan Fontenot
2014-05-28 20:47   ` Dave Hansen
2014-05-29  8:48     ` DX Cui [this message]

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