linux-kernel - Re: [PATCH] mm/slab: Fix undefined init_cache_node

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 for Android: free password hash cracker in your pocket

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

Date:   Thu, 23 Mar 2023 09:25:37 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        linux-mm@...ck.org, linux-sh@...r.kernel.org,
        linux-kernel@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH] mm/slab: Fix undefined init_cache_node_node() for NUMA
 and !SMP

Hi Matthew,

On Wed, Mar 22, 2023 at 5:47 PM Matthew Wilcox <willy@...radead.org> wrote:
> On Wed, Mar 22, 2023 at 09:16:55AM -0700, Dave Hansen wrote:
> > On 3/21/23 09:40, Matthew Wilcox wrote:
> > > On Tue, Mar 21, 2023 at 09:30:59AM +0100, Geert Uytterhoeven wrote:
> > >> -#if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
> > >> +#if defined(CONFIG_NUMA) || defined(CONFIG_SMP)
> > > I'm amused by the thought of CONFIG_NUMA without CONFIG_SMP.
> > > Is it possible to have one node with memory and a single CPU, then
> > > another node with memory and no CPU?
> >
> > It's _possible_ for sure, just unlikely.  The most likely place these
> > days is probably a teensy tiny VM that just happens to have some
> > performance-differentiated memory exposed to it for some reason.  Maybe
> > it's got a slice of slow PMEM or fast High-Bandwidth memory for whatever
> > reason.
>
> Right, you can construct such a system, but do we support the CONFIG
> options of NUMA enabled and SMP disabled?  It seems so niche that we
> shouldn't be spending time testing that combination.

SH has been using this for a long time.

It's supported. Dave just forgot to update the #ifdef around the
definition of init_cache_node_node() when updating an #ifdef around
a code block that contains one of the callers.

P.S. To me, this discussion reminds me of the old discussion about
     discontigmem without NUMA. Yes, not all systems are PCs with
     contiguous memory on a single fast bus ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds