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From:   Rafael David Tinoco <rafael.tinoco@linaro.org>
To:     Alexey Dobriyan <adobriyan@gmail.com>
Cc:     gorcunov@gmail.com, akpm@linux-foundation.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, shuah@kernel.org
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References: <20181108111105.GC13195@uranus.lan>
 <20181109113036.21512-1-rafael.tinoco@linaro.org>
 <20181110174727.GA26417@avx2>
Date:   Sat, 10 Nov 2018 15:56:03 -0200
In-Reply-To: <20181110174727.GA26417@avx2>
Subject: Re: [PATCH] proc: fix and merge proc-self-map-file tests
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat, Nov 10, 2018, at 3:47 PM, Alexey Dobriyan wrote:
> On Fri, Nov 09, 2018 at 09:30:36AM -0200, Rafael David Tinoco wrote:
> > Merge proc-self-map-files tests into one since this test should focus in
> > testing readlink in /proc/self/map_files/* only, and not trying to test
> > mapping virtual address 0.
> > 
> > Lowest virtual address for user space mapping in other architectures,
> > like arm, is *at least* *(PAGE_SIZE * 2) and NULL hint does not
> > guarantee that when MAP_FIXED flag, important to this test, is given.
> > This patch also fixes this issue in remaining test.
> 
> > -	p = mmap(NULL, PAGE_SIZE, PROT_NONE, MAP_PRIVATE|MAP_FILE, fd, 0);
> > +	p = mmap((void *) (2 * PAGE_SIZE), PAGE_SIZE, PROT_NONE,
> 
> I don't know ARM. Is this 2 page limitation a limitation of hardware or
> kernel's?

Kernel:
https://bugs.linaro.org/show_bug.cgi?id=3782#c7