linux-kernel - Re: [PATCH] selftests/vm: Update max va test to check for high address return.

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Date:   Wed, 28 Feb 2018 13:58:04 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc:     akpm@...ux-foundation.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] selftests/vm: Update max va test to check for high
 address return.

On Wed, Feb 28, 2018 at 09:28:30AM +0530, Aneesh Kumar K.V wrote:
> mmap(-1,..) is expected to search from max supported VA top down. It should find
> an address above ADDR_SWITCH_HINT. Explicitly check for this.

Hm. I don't think this correct. -1 means the application supports any
address, not restricted to 47-bit address space. It doesn't mean the
application *require* the address to be above 47-bit.

At least on x86, -1 just shift upper boundary of address range where we
can look for unmapped area.

-- 
 Kirill A. Shutemov