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From: Michal Hocko <mhocko@kernel.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rui Teng <rui.teng@linux.vnet.ibm.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@windriver.com>,
	Santhosh G <santhog4@in.ibm.com>
Subject: Re: [PATCH] memory-hotplug: Fix bad area access on dissolve_free_huge_pages()
Date: Wed, 21 Sep 2016 14:05:08 +0200	[thread overview]
Message-ID: <20160921120507.GG10300@dhcp22.suse.cz> (raw)
In-Reply-To: <57E17531.6050008@linux.intel.com>

On Tue 20-09-16 10:43:13, Dave Hansen wrote:
> On 09/20/2016 08:52 AM, Rui Teng wrote:
> > On 9/20/16 10:53 PM, Dave Hansen wrote:
> ...
> >> That's good, but aren't we still left with a situation where we've
> >> offlined and dissolved the _middle_ of a gigantic huge page while the
> >> head page is still in place and online?
> >>
> >> That seems bad.
> >>
> > What about refusing to change the status for such memory block, if it
> > contains a huge page which larger than itself? (function
> > memory_block_action())
> 
> How will this be visible to users, though?  That sounds like you simply
> won't be able to offline memory with gigantic huge pages.

I might be missing something but Is this any different from a regular
failure when the memory cannot be freed? I mean
/sys/devices/system/memory/memory API doesn't give you any hint whether
the memory in the particular block is used and
unmigrateable.

-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2016-09-21 12:05 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-13  8:39 Rui Teng
2016-09-13 17:32 ` Dave Hansen
2016-09-14 16:33   ` Rui Teng
2016-09-14 16:37     ` Dave Hansen
2016-09-16 13:58       ` Rui Teng
2016-09-16 16:25         ` Dave Hansen
2016-09-20 14:45           ` Rui Teng
2016-09-20 14:53             ` Dave Hansen
2016-09-20 15:52               ` Rui Teng
2016-09-20 17:43                 ` Dave Hansen
2016-09-21 12:05                   ` Michal Hocko [this message]
2016-09-21 16:04                     ` Dave Hansen
2016-09-21 16:27                       ` Michal Hocko
2016-09-21 16:32                         ` Dave Hansen
2016-09-21 16:52                           ` Michal Hocko

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