linux-kernel - Re: [PATCH 1/3] powerpc/numa: Set numa

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]

Message-ID: <CAAmzW4ME_WLYZPCt4+82RNKstv-H=LK5MKGGJR=6ha-ALS+FSw@mail.gmail.com>
Date:   Mon, 16 Mar 2020 17:15:19 +0900
From:   Joonsoo Kim <js1304@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Sachin Sant <sachinp@...ux.vnet.ibm.com>,
        Michal Hocko <mhocko@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Mel Gorman <mgorman@...e.de>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Christopher Lameter <cl@...ux.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH 1/3] powerpc/numa: Set numa_node for all possible cpus

2020년 3월 13일 (금) 오후 8:38, Vlastimil Babka <vbabka@...e.cz>님이 작성:
>
> On 3/13/20 12:04 PM, Srikar Dronamraju wrote:
> >> I lost all the memory about it. :)
> >> Anyway, how about this?
> >>
> >> 1. make node_present_pages() safer
> >> static inline node_present_pages(nid)
> >> {
> >> if (!node_online(nid)) return 0;
> >> return (NODE_DATA(nid)->node_present_pages);
> >> }
> >>
> >
> > Yes this would help.
>
> Looks good, yeah.
>
> >> 2. make node_to_mem_node() safer for all cases
> >> In ppc arch's mem_topology_setup(void)
> >> for_each_present_cpu(cpu) {
> >>  numa_setup_cpu(cpu);
> >>  mem_node = node_to_mem_node(numa_mem_id());
> >>  if (!node_present_pages(mem_node)) {
> >>   _node_numa_mem_[numa_mem_id()] = first_online_node;
> >>  }
> >> }
> >>
> >
> > But here as discussed above, we miss the case of possible but not present nodes.
> > For such nodes, the above change may not update, resulting in they still
> > having 0. And node 0 can be only possible but not present.

Oops, I don't read full thread so miss the case.

> So is there other way to do the setup so that node_to_mem_node() returns an
> online+present node when called for any possible node?

Two changes seems to be sufficient.

1. initialize all node's _node_numa_mem_[] = first_online_node in
mem_topology_setup()
2. replace the node with online+present node for _node_to_mem_node_[]
in set_cpu_numa_mem().

 static inline void set_cpu_numa_mem(int cpu, int node)
 {
        per_cpu(_numa_mem_, cpu) = node;
+       if (!node_present_pages(node))
+               node = first_online_node;
        _node_numa_mem_[cpu_to_node(cpu)] = node;
 }
 #endif

With these two change, we can safely call node_to_mem_node() anywhere.

Thanks.