linux-kernel - Re: [PATCH RFCv2 3/4] mm/memory_hotplug: Introduce and use more memory types

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] [day] [month] [year] [list]

Message-ID: <b8e03810-41d6-55cb-9546-62c73c7f4d7f@redhat.com>
Date:   Tue, 4 Dec 2018 10:47:33 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Michal Suchánek <msuchanek@...e.de>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-ia64@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
        linux-acpi@...r.kernel.org, devel@...uxdriverproject.org,
        xen-devel@...ts.xenproject.org, x86@...nel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Rashmica Gupta <rashmica.g@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Pavel Tatashin <pavel.tatashin@...rosoft.com>,
        Balbir Singh <bsingharora@...il.com>,
        Michael Neuling <mikey@...ling.org>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        YueHaibing <yuehaibing@...wei.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        "mike.travis@....com" <mike.travis@....com>,
        Oscar Salvador <osalvador@...e.de>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Mathieu Malaterre <malat@...ian.org>,
        Michal Hocko <mhocko@...e.com>,
        Arun KS <arunks@...eaurora.org>,
        Andrew Banman <andrew.banman@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH RFCv2 3/4] mm/memory_hotplug: Introduce and use more
 memory types

On 04.12.18 10:44, Michal Suchánek wrote:
> On Fri, 30 Nov 2018 18:59:21 +0100
> David Hildenbrand <david@...hat.com> wrote:
> 
>> Let's introduce new types for different kinds of memory blocks and use
>> them in existing code. As I don't see an easy way to split this up,
>> do it in one hunk for now.
>>
>> acpi:
>>  Use DIMM or DIMM_UNREMOVABLE depending on hotremove support in the kernel.
>>  Properly change the type when trying to add memory that was already
>>  detected and used during boot (so this memory will correctly end up as
>>  "acpi" in user space).
>>
>> pseries:
>>  Use DIMM or DIMM_UNREMOVABLE depending on hotremove support in the kernel.
>>  As far as I see, handling like in the acpi case for existing blocks is
>>  not required.
>>
>> probed memory from user space:
>>  Use DIMM_UNREMOVABLE as there is no interface to get rid of this code
>>  again.
>>
>> hv_balloon,xen/balloon:
>>  Use BALLOON. As simple as that :)
>>
>> s390x/sclp:
>>  Use a dedicated type S390X_STANDBY as this type of memory and it's
>>  semantics are very s390x specific.
>>
>> powernv/memtrace:
>>  Only allow to use BOOT memory for memtrace. I consider this code in
>>  general dangerous, but we have to keep it working ... most probably just
>>  a debug feature.
> 
> I don't think it should be arbitrarily restricted like that.
> 

Well code that "randomly" offlines/onlines/removes/adds memory blocks
that it does not own (hint: nobody else in the kernel does that), should
be restricted to types we can guarantee to work.

> Thanks
> 
> Michal
> 


-- 

Thanks,

David / dhildenb