linux-kernel - Re: ppc elf_map breakage with MAP_FIXED

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Message-Id: <082aa008-c56a-681d-0949-107245603a97@linux.vnet.ibm.com>
Date:   Tue, 23 Jan 2018 16:55:18 +0530
From:   Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>, akpm@...ux-foundation.org,
        mm-commits@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-next@...r.kernel.org, sfr@...b.auug.org.au,
        broonie@...nel.org
Subject: Re: ppc elf_map breakage with MAP_FIXED_NOREPLACE

On 01/17/2018 01:37 PM, Michal Hocko wrote:
> On Thu 11-01-18 15:38:37, Anshuman Khandual wrote:
>> On 01/09/2018 09:43 PM, Michal Hocko wrote:
> [...]
>>> Did you manage to catch _who_ is requesting that anonymous mapping? Do
>>> you need a help with the debugging patch?
>>
>> Not yet, will get back on this.
> 
> ping?

Hey Michal,

Missed this thread, my apologies. This problem is happening only with
certain binaries like 'sed', 'tmux', 'hostname', 'pkg-config' etc. As
you had mentioned before the map request collision is happening on
[10030000, 10040000] and [10030000, 10040000] ranges only which is
just a single PAGE_SIZE. You asked previously that who might have
requested the anon mapping which is already present in there ? Would
not that be the same process itself ? I am bit confused. Would it be
helpful to trap all the mmap() requests from any of the binaries
and see where we might have created that anon mapping ?