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From: Igor Mammedov <imammedo@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Jerome Glisse <jglisse@redhat.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Kani Toshimitsu <toshi.kani@hpe.com>,
	slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE
Date: Wed, 24 May 2017 15:30:17 +0200	[thread overview]
Message-ID: <20170524153017.7a66368d@nial.brq.redhat.com> (raw)
In-Reply-To: <20170524122411.25212-3-mhocko@kernel.org>

On Wed, 24 May 2017 14:24:11 +0200
Michal Hocko <mhocko@kernel.org> wrote:

[...]
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
[...]
> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
maybe dumb question but, is it really true that kernel won't ever
do kernel allocations from movable zone?

looking at kmalloc(slab): we can get here:

get_page_from_freelist() ->
    rmqueue() ->
        __rmqueue() ->
            __rmqueue_fallback() ->
                find_suitable_fallback()

and it might return movable fallback and page could be stolen from there.

WARNING: multiple messages have this Message-ID (diff)
From: Igor Mammedov <imammedo@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Jerome Glisse <jglisse@redhat.com>,
	Reza Arbab <arbab@linux.vnet.ibm.com>,
	Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
	qiuxishi@huawei.com, Kani Toshimitsu <toshi.kani@hpe.com>,
	slaoub@gmail.com, Joonsoo Kim <js1304@gmail.com>,
	Andi Kleen <ak@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	Daniel Kiper <daniel.kiper@oracle.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE
Date: Wed, 24 May 2017 15:30:17 +0200	[thread overview]
Message-ID: <20170524153017.7a66368d@nial.brq.redhat.com> (raw)
In-Reply-To: <20170524122411.25212-3-mhocko@kernel.org>

On Wed, 24 May 2017 14:24:11 +0200
Michal Hocko <mhocko@kernel.org> wrote:

[...]
> index facc20a3f962..ec7d6ae01c96 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2246,8 +2246,11 @@
[...]
> +			movable. This means that the memory of such nodes
> +			will be usable only for movable allocations which
> +			rules out almost all kernel allocations. Use with
> +			caution!
maybe dumb question but, is it really true that kernel won't ever
do kernel allocations from movable zone?

looking at kmalloc(slab): we can get here:

get_page_from_freelist() ->
    rmqueue() ->
        __rmqueue() ->
            __rmqueue_fallback() ->
                find_suitable_fallback()

and it might return movable fallback and page could be stolen from there.

--
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  parent reply	other threads:[~2017-05-24 13:30 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-24 12:24 [RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE Michal Hocko
2017-05-24 12:24 ` Michal Hocko
2017-05-24 12:24 ` [RFC PATCH 1/2] mm, memory_hotplug: drop artificial restriction on online/offline Michal Hocko
2017-05-24 12:24   ` Michal Hocko
2017-05-24 12:44   ` Vlastimil Babka
2017-05-24 12:44     ` Vlastimil Babka
2017-05-24 12:55     ` Michal Hocko
2017-05-24 12:55       ` Michal Hocko
2017-05-24 21:50   ` Reza Arbab
2017-05-24 21:50     ` Reza Arbab
2017-05-25  6:28     ` Michal Hocko
2017-05-25  6:28       ` Michal Hocko
2017-05-24 12:24 ` [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE Michal Hocko
2017-05-24 12:24   ` Michal Hocko
2017-05-24 12:53   ` Vlastimil Babka
2017-05-24 12:53     ` Vlastimil Babka
2017-05-24 13:42     ` Michal Hocko
2017-05-24 13:42       ` Michal Hocko
2017-05-24 15:17       ` Vlastimil Babka
2017-05-24 15:17         ` Vlastimil Babka
2017-05-25  6:27         ` Michal Hocko
2017-05-25  6:27           ` Michal Hocko
2017-05-25  8:41           ` Vlastimil Babka
2017-05-25  8:41             ` Vlastimil Babka
2017-05-24 13:30   ` Igor Mammedov [this message]
2017-05-24 13:30     ` Igor Mammedov
2017-05-24 13:50     ` Michal Hocko
2017-05-24 13:50       ` Michal Hocko
2017-05-24 21:51   ` Reza Arbab
2017-05-24 21:51     ` Reza Arbab
2017-05-25 12:03 ` [RFC PATCH 0/2] remove CONFIG_MOVABLE_NODE Michal Hocko
2017-05-25 12:03   ` Michal Hocko

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