linux-kernel - Re: collision between ZONE_MOVABLE and memblock allocations

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: <20230719222604.GB3528218@google.com>
Date:   Wed, 19 Jul 2023 16:26:04 -0600
From:   Ross Zwisler <zwisler@...gle.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        David Hildenbrand <david@...hat.com>
Subject: Re: collision between ZONE_MOVABLE and memblock allocations

On Wed, Jul 19, 2023 at 08:44:34AM +0300, Mike Rapoport wrote:
> 3. Switch memblock to use bottom up allocations. Historically memblock
> allocated memory from the top to avoid corrupting the kernel image and to
> avoid exhausting precious ZONE_DMA. I believe we can use bottom-up
> allocations with lower limit of memblock allocations set to 16M.
> 
> With the hack below no memblock allocations will end up in ZONE_MOVABLE:

Yep, I've confirmed that for my use cases at least this does the trick, thank
you!  I had thought about moving the memblock allocations, but had no idea it
was (basically) already supported and thought it'd be much riskier than just
adjusting where ZONE_MOVABLE lived.

Is there a reason for this to not be a real option for users, maybe per a
kernel config knob or something?  I'm happy to explore other options in this
thread, but this is doing the trick so far.