linux-kernel - Re: [PATCH] DAX: warn when kmem regions are truncated for memory block alignment.

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: <a65fd672-6864-433c-8c82-276cb34636f9@redhat.com>
Date: Tue, 1 Apr 2025 17:19:28 +0200
From: David Hildenbrand <david@...hat.com>
To: Gregory Price <gourry@...rry.net>
Cc: dan.j.williams@...el.com, nvdimm@...ts.linux.dev,
 linux-kernel@...r.kernel.org, kernel-team@...a.com,
 vishal.l.verma@...el.com, dave.jiang@...el.com, linux-cxl@...r.kernel.org
Subject: Re: [PATCH] DAX: warn when kmem regions are truncated for memory
 block alignment.

On 01.04.25 17:16, Gregory Price wrote:
> On Tue, Apr 01, 2025 at 04:50:40PM +0200, David Hildenbrand wrote:
>>
>> Oh, you mean with the whole memmap_on_memory thing. Even with that, using
>> 2GB memory blocks would only fit a single 1GB memory block ... and it
>> requires ZONE_NORMAL.
>>
>> For ordinary boot memory, the 1GB behavior should be independent of the
>> memory block size (a 1GB page can span multiple blocks as long as they are
>> in the same zone), which is the most important thing.
>>
>> So I don't think it's a concern for DAX right now. Whoever needs that, can
>> disable the memmap_on_memory option.
>>
> 
> If we think it's not a major issue then I'll rebase onto latest and push
> a v9.  I think there was one minor nit left.
> 
> I suppose folks can complain to their vendors about alignment if they
> don't want 60000 memoryN entries on their huge-memory-systems.
> 
> Probably we still want this warning?  Silent truncation still seems
> undesirable.

Yes, it's valuable I think. But should it be a warning or rather an info?

-- 
Cheers,

David / dhildenb