Messages in this thread | | | Date | Thu, 3 Jan 2013 13:24:17 +0100 | From | Petr Holasek <> | Subject | Re: [PATCH v7 1/2] KSM: numa awareness sysfs knob |
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Hi Simon,
On Mon, 31 Dec 2012, Simon Jeons wrote: > On Fri, 2012-12-28 at 02:32 +0100, Petr Holasek wrote: > > > > v7: - added sysfs ABI documentation for KSM > > Hi Petr, > > How you handle "memory corruption because the ksm page still points to > the stable_node that has been freed" mentioned by Andrea this time? >
<snip>
> > > > + /* > > + * If tree_page has been migrated to another NUMA node, it > > + * will be flushed out and put into the right unstable tree > > + * next time: only merge with it if merge_across_nodes. > > Why? Do you mean swap based migration? Or where I miss ....? >
It can be physical page migration triggered by page compaction, memory hotplug or some NUMA sched/memory balancing algorithm developed recently.
> > + * Just notice, we don't have similar problem for PageKsm > > + * because their migration is disabled now. (62b61f611e) > > + */
Migration of KSM pages is disabled now, you can look into ^^^ commit and changes introduced to migrate.c.
> > + if (!ksm_merge_across_nodes && page_to_nid(tree_page) != nid) { > > + put_page(tree_page); > > + return NULL; > > + } > > + > > ret = memcmp_pages(page, tree_page);
</snip>
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