From: Marek Szyprowski <m.szyprowski@samsung.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Rabin Vincent <rabin@rab.in>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: CMA and zone watermarks
Date: Tue, 09 Oct 2012 05:12:21 +0200 [thread overview]
Message-ID: <50739615.9080205@samsung.com> (raw)
In-Reply-To: <20121009031023.GF13817@bbox>
Hello,
On 10/9/2012 5:10 AM, Minchan Kim wrote:
> On Mon, Oct 08, 2012 at 05:41:14PM +0200, Rabin Vincent wrote:
>> It appears that when CMA is enabled, the zone watermarks are not properly
>> respected, leading to for example GFP_NOWAIT allocations getting access to the
>> high pools.
>>
>> I ran the following test code which simply allocates pages with GFP_NOWAIT
>> until it fails, and then tries GFP_ATOMIC. Without CMA, the GFP_ATOMIC
>> allocation succeeds, with CMA, it fails too.
>
> Good spot. By wrong zone_watermark_check, it can consume reserved memory pool.
That was the main reason for the Bartek's research.
>> Logs attached (includes my patch which prints the migration type in the failure
>> message http://marc.info/?l=linux-mm&m=134971041701306&w=2), taken on 3.6
>> kernel.
>>
>
> Fortunately, recently, Bart sent a patch about that.
> http://marc.info/?l=linux-mm&m=134763299016693&w=2
>
> Could you test above patches in your kernel?
> You have to apply [2/4], [3/4], [4/4] and don't need [1/4].
AFAIR without patch [1/4], free cma page counter will go below zero and
weird thing will happen, so better apply the complete patchset.
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
next prev parent reply other threads:[~2012-10-09 3:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-08 15:41 CMA and zone watermarks Rabin Vincent
2012-10-09 0:37 ` Marek Szyprowski
2012-10-09 15:25 ` Rabin Vincent
2012-10-09 3:10 ` Minchan Kim
2012-10-09 3:12 ` Marek Szyprowski [this message]
2012-10-09 4:43 ` Minchan Kim
2012-10-09 4:53 ` Marek Szyprowski
2012-10-09 5:07 ` Minchan Kim
2012-10-09 5:16 ` Marek Szyprowski
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