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Date: Fri, 27 Jan 2012 11:53:29 +0100
From: Marek Szyprowski <m.szyprowski@samsung.com>
Subject: RE: [Linaro-mm-sig] [PATCH 12/15] drivers: add Contiguous Memory
 Allocator
In-reply-to: <CADMYwHw1B4RNV_9BqAg_M70da=g69Z3kyo5Cr6izCMwJ9LAtvA@mail.gmail.com>
To: "'Ohad Ben-Cohen'" <ohad@wizery.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-media@vger.kernel.org, linux-mm@kvack.org,
        linaro-mm-sig@lists.linaro.org,
        "'Daniel Walker'" <dwalker@codeaurora.org>,
        "'Russell King'" <linux@arm.linux.org.uk>,
        "'Arnd Bergmann'" <arnd@arndb.de>,
        "'Jonathan Corbet'" <corbet@lwn.net>, "'Mel Gorman'" <mel@csn.ul.ie>,
        "'Michal Nazarewicz'" <mina86@mina86.com>,
        "'Dave Hansen'" <dave@linux.vnet.ibm.com>,
        "'Jesse Barker'" <jesse.barker@linaro.org>,
        "'Kyungmin Park'" <kyungmin.park@samsung.com>,
        "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'KAMEZAWA Hiroyuki'" <kamezawa.hiroyu@jp.fujitsu.com>
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Hi Ohad,

On Friday, January 27, 2012 10:44 AM Ohad Ben-Cohen wrote:

> With v19, I can't seem to allocate big regions anymore (e.g. 101MiB).
> In particular, this seems to fail:
> 
> On Thu, Jan 26, 2012 at 11:00 AM, Marek Szyprowski
> <m.szyprowski@samsung.com> wrote:
> > +static int cma_activate_area(unsigned long base_pfn, unsigned long count)
> > +{
> > +       unsigned long pfn = base_pfn;
> > +       unsigned i = count >> pageblock_order;
> > +       struct zone *zone;
> > +
> > +       WARN_ON_ONCE(!pfn_valid(pfn));
> > +       zone = page_zone(pfn_to_page(pfn));
> > +
> > +       do {
> > +               unsigned j;
> > +               base_pfn = pfn;
> > +               for (j = pageblock_nr_pages; j; --j, pfn++) {
> > +                       WARN_ON_ONCE(!pfn_valid(pfn));
> > +                       if (page_zone(pfn_to_page(pfn)) != zone)
> > +                               return -EINVAL;
> 
> The above WARN_ON_ONCE is triggered, and then the conditional is
> asserted (page_zone() retuns a "Movable" zone, whereas zone is
> "Normal") and the function fails.
> 
> This happens to me on OMAP4 with your 3.3-rc1-cma-v19 branch (and a
> bunch of remoteproc/rpmsg patches).
> 
> Do big allocations work for you ?

I've tested it with 256MiB on Exynos4 platform. Could you check if the
problem also appears on 3.2-cma-v19 branch (I've uploaded it a few hours
ago) and 3.2-cma-v18? Both are available on our public repo:
git://git.infradead.org/users/kmpark/linux-samsung/

The above code has not been changed since v16, so I'm really surprised 
that it causes problems. Maybe the memory configuration or layout has 
been changed in 3.3-rc1 for OMAP4?

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center