linux-kernel - Re: [PATCH RFC] mm: mmap: Change DEFAULT_MAX_MAP_COUNT to INT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <fa76bdf0-81e4-4f7c-9dce-217ff8b464ee@redhat.com>
Date: Fri, 30 Aug 2024 17:24:10 +0200
From: David Hildenbrand <david@...hat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Petr Spacek <pspacek@....org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Vlastimil Babka <vbabka@...e.cz>, Liam Howlett <liam.howlett@...cle.com>
Subject: Re: [PATCH RFC] mm: mmap: Change DEFAULT_MAX_MAP_COUNT to INT_MAX

On 30.08.24 13:41, Lorenzo Stoakes wrote:
> On Fri, Aug 30, 2024 at 11:56:36AM GMT, Petr Spacek wrote:
>> From: Petr Spacek <pspacek@....org>
>>
>> Raise default sysctl vm.max_map_count to INT_MAX, which effectively
>> disables the limit for all sane purposes. The sysctl is kept around in
>> case there is some use-case for this limit.
>>
>> The old default value of vm.max_map_count=65530 provided compatibility
>> with ELF format predating year 2000 and with binutils predating 2010. At
>> the same time the old default caused issues with applications deployed
>> in 2024.
>>
>> State since 2012: Linux 3.2.0 correctly generates coredump from a
>> process with 100 000 mmapped files. GDB 7.4.1, binutils 2.22 work with
>> this coredump fine and can actually read data from the mmaped addresses.
>>
>> Signed-off-by: Petr Spacek <pspacek@....org>
> 
> NACK.

Ageed, I could have sworn I NACKed a similar patch just months ago.

If you use that many memory mappings, you re doing something very, very 
wrong.

-- 
Cheers,

David / dhildenb