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From: Johannes Weiner <hannes@cmpxchg.org>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Nazarewicz <mina86@mina86.com>,
	Michal Hocko <mhocko@suse.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	stable@vger.kernel.org
Subject: Re: [PATCH v2] mm/cma: fix alloc_contig_range ret code/potential leak
Date: Mon, 27 Nov 2017 16:59:06 +0000	[thread overview]
Message-ID: <20171127165906.GA16092@cmpxchg.org> (raw)
In-Reply-To: <20171122185214.25285-1-mike.kravetz@oracle.com>

On Wed, Nov 22, 2017 at 10:52:14AM -0800, Mike Kravetz wrote:
> If the call __alloc_contig_migrate_range() in alloc_contig_range
> returns -EBUSY, processing continues so that test_pages_isolated()
> is called where there is a tracepoint to identify the busy pages.
> However, it is possible for busy pages to become available between
> the calls to these two routines.  In this case, the range of pages
> may be allocated.   Unfortunately, the original return code (ret
> == -EBUSY) is still set and returned to the caller.  Therefore,
> the caller believes the pages were not allocated and they are leaked.
> 
> Update comment to indicate that allocation is still possible even if
> __alloc_contig_migrate_range returns -EBUSY.  Also, clear return code
> in this case so that it is not accidentally used or returned to caller.
> 
> Fixes: 8ef5849fa8a2 ("mm/cma: always check which page caused allocation failure")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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  parent reply	other threads:[~2017-11-27 16:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-20 19:39 [PATCH 0/1] mm/cma: fix alloc_contig_range ret code/potential leak Mike Kravetz
2017-11-20 19:39 ` [PATCH 1/1] " Mike Kravetz
2017-11-21  7:53   ` Vlastimil Babka
2017-11-21 13:06     ` Michal Hocko
2017-11-21 13:04   ` Michal Hocko
2017-11-21 14:20   ` Michal Nazarewicz
2017-11-22 12:00   ` Johannes Weiner
2017-11-22 17:46     ` Mike Kravetz
2017-11-22 18:52       ` [PATCH v2] " Mike Kravetz
2017-11-23  8:05         ` Vlastimil Babka
2017-11-23  9:19         ` Michal Hocko
2017-11-27 16:59         ` Johannes Weiner [this message]
2017-11-29  5:38         ` Joonsoo Kim

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