Re: [PATCH 8/11] ksm: make !merge_across_nodes migration safe

2013-01-27 Thread Simon Jeons
On Fri, 2013-01-25 at 18:05 -0800, Hugh Dickins wrote: > The new KSM NUMA merge_across_nodes knob introduces a problem, when it's > set to non-default 0: if a KSM page is migrated to a different NUMA node, > how do we migrate its stable node to the right tree? And what if that > collides with an e

Re: [PATCH 8/11] ksm: make !merge_across_nodes migration safe

2013-01-27 Thread Hugh Dickins
On Sun, 27 Jan 2013, Simon Jeons wrote: > On Fri, 2013-01-25 at 18:05 -0800, Hugh Dickins wrote: > > @@ -1344,10 +1401,29 @@ static void cmp_and_merge_page(struct pa > > unsigned int checksum; > > int err; > > > > - remove_rmap_item_from_tree(rmap_item); > > + stable_node = page_stabl

Re: [PATCH 8/11] ksm: make !merge_across_nodes migration safe

2013-01-27 Thread Simon Jeons
On Fri, 2013-01-25 at 18:05 -0800, Hugh Dickins wrote: > The new KSM NUMA merge_across_nodes knob introduces a problem, when it's > set to non-default 0: if a KSM page is migrated to a different NUMA node, > how do we migrate its stable node to the right tree? And what if that > collides with an e

[PATCH 8/11] ksm: make !merge_across_nodes migration safe

2013-01-25 Thread Hugh Dickins
The new KSM NUMA merge_across_nodes knob introduces a problem, when it's set to non-default 0: if a KSM page is migrated to a different NUMA node, how do we migrate its stable node to the right tree? And what if that collides with an existing stable node? ksm_migrate_page() can do no more than it