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Date: Tue, 2 May 2017 10:43:23 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Xishi Qiu <qiuxishi@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
        Joonsoo Kim <js1304@gmail.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Rik van Riel <riel@redhat.com>, Shakeel Butt <shakeelb@google.com>,
        Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        zhong jiang <zhongjiang@huawei.com>
Subject: Re: [RFC] dev/mem: "memtester -p 0x6c80000000000 10G" cause crash
Message-ID: <20170502084323.GG14593@dhcp22.suse.cz>
References: <59083C5B.5080204@huawei.com>
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On Tue 02-05-17 15:59:23, Xishi Qiu wrote:
> Hi, I use "memtester -p 0x6c80000000000 10G" to test physical address 0x6c80000000000
> Because this physical address is invalid, and valid_mmap_phys_addr_range()
> always return 1, so it causes crash.
> 
> My question is that should the user assure the physical address is valid?

We already seem to be checking range_is_allowed(). What is your
CONFIG_STRICT_DEVMEM setting? The code seems to be rather confusing but
my assumption is that you better know what you are doing when mapping
this file.

> ...
> [ 169.147578] ? panic+0x1f1/0x239
> [ 169.150789] oops_end+0xb8/0xd0
> [ 169.153910] pgtable_bad+0x8a/0x95
> [ 169.157294] __do_page_fault+0x3aa/0x4a0
> [ 169.161194] do_page_fault+0x30/0x80
> [ 169.164750] ? do_syscall_64+0x175/0x180
> [ 169.168649] page_fault+0x28/0x30
> 
> Thanks,
> Xishi Qiu

-- 
Michal Hocko
SUSE Labs