---------- Forwarded message ----------
From: David Rientjes <[email protected]>
Date: Thu, Apr 21, 2011 at 01:12
Subject: Re: [PATCH v3] mm: make expand_downwards symmetrical to expand_upwards
To: James Bottomley <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>, Pekka Enberg
<[email protected]>, Christoph Lameter <[email protected]>, Michal Hocko
<[email protected]>, Andrew Morton <[email protected]>, Hugh
Dickins <[email protected]>, [email protected], LKML
<[email protected]>, [email protected], Ingo
Molnar <[email protected]>, x86 maintainers <[email protected]>


On Wed, 20 Apr 2011, James Bottomley wrote:

> > This is probably because the parisc's DISCONTIGMEM memory ranges don't
> > have bits set in N_NORMAL_MEMORY.
> >
> > diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
> > --- a/arch/parisc/mm/init.c
> > +++ b/arch/parisc/mm/init.c
> > @@ -266,8 +266,10 @@ static void __init setup_bootmem(void)
> >     }
> >     memset(pfnnid_map, 0xff, sizeof(pfnnid_map));
> >
> > -   for (i = 0; i < npmem_ranges; i++)
> > +   for (i = 0; i < npmem_ranges; i++) {
> > +           node_set_state(i, N_NORMAL_MEMORY);
> >             node_set_online(i);
> > +   }
> >  #endif
>
> Yes, this seems to be the missing piece that gets it to boot.  We really
> need this in generic code, unless someone wants to run through all the
> other arch's doing it ...
>

Looking at all other architectures that allow ARCH_DISCONTIGMEM_ENABLE, we
already know x86 is fine, avr32 disables ARCH_DISCONTIGMEM_ENABLE entirely
because its code only brings online node 0, and tile already sets the bit
in N_NORMAL_MEMORY correctly when bringing a node online, probably because
it was introduced after the various node state masks were added in
7ea1530ab3fd back in October 2007.

So we're really only talking about alpha, ia64, m32r, m68k, and mips and
it only seems to matter when using CONFIG_SLUB, which isn't surprising
when greping for it:

       $ grep -r N_NORMAL_MEMORY mm/*
       mm/memcontrol.c:        if (!node_state(node, N_NORMAL_MEMORY))
       mm/memcontrol.c:                if (!node_state(node, N_NORMAL_MEMORY))
       mm/page_alloc.c:        [N_NORMAL_MEMORY] = { { [0] = 1UL } },
       mm/page_alloc.c:
node_set_state(zone_to_nid(zone), N_NORMAL_MEMORY);
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:              for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:              for_each_node_state(node, N_NORMAL_MEMORY) {
       mm/slub.c:      for_each_node_state(node, N_NORMAL_MEMORY)

Those memory controller occurrences only result in it passing a node id of
-1 to kmalloc_node() which means no specific node target, and that's fine
for DISCONTIGMEM since we don't care about any proximity between memory
ranges.

This should fix the remaining architectures so they can use CONFIG_SLUB,
but I hope it can be tested by the individual arch maintainers like you
did for parisc.

diff --git a/arch/alpha/mm/numa.c b/arch/alpha/mm/numa.c
--- a/arch/alpha/mm/numa.c
+++ b/arch/alpha/mm/numa.c
@@ -245,6 +245,7 @@ setup_memory_node(int nid, void *kernel_end)
                       bootmap_size, BOOTMEM_DEFAULT);
       printk(" reserving pages %ld:%ld\n", bootmap_start,
bootmap_start+PFN_UP(bootmap_size));

+       node_set_state(nid, N_NORMAL_MEMORY);
       node_set_online(nid);
 }

diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
--- a/arch/ia64/mm/discontig.c
+++ b/arch/ia64/mm/discontig.c
@@ -573,6 +573,8 @@ void __init find_memory(void)
                                 map>>PAGE_SHIFT,
                                 bdp->node_min_pfn,
                                 bdp->node_low_pfn);
+               if (node_present_pages(node))
+                       node_set_state(node, N_NORMAL_MEMORY);
       }

       efi_memmap_walk(filter_rsvd_memory, free_node_bootmem);
diff --git a/arch/m32r/kernel/setup.c b/arch/m32r/kernel/setup.c
--- a/arch/m32r/kernel/setup.c
+++ b/arch/m32r/kernel/setup.c
@@ -247,7 +247,9 @@ void __init setup_arch(char **cmdline_p)

 #ifdef CONFIG_DISCONTIGMEM
       nodes_clear(node_online_map);
+       node_set_state(0, N_NORMAL_MEMORY);     /* always has memory */
       node_set_online(0);
+       node_set_state(1, N_NORMAL_MEMORY);     /* always has memory */
       node_set_online(1);
 #endif /* CONFIG_DISCONTIGMEM */

diff --git a/arch/m68k/mm/init_mm.c b/arch/m68k/mm/init_mm.c
--- a/arch/m68k/mm/init_mm.c
+++ b/arch/m68k/mm/init_mm.c
@@ -59,6 +59,8 @@ void __init m68k_setup_node(int node)
       }
 #endif
       pg_data_map[node].bdata = bootmem_node_data + node;
+       if (node_present_pages(node))
+               node_set_state(node, N_NORMAL_MEMORY);
       node_set_online(node);
 }

diff --git a/arch/mips/sgi-ip27/ip27-memory.c b/arch/mips/sgi-ip27/ip27-memory.c
--- a/arch/mips/sgi-ip27/ip27-memory.c
+++ b/arch/mips/sgi-ip27/ip27-memory.c
@@ -471,6 +471,8 @@ void __init paging_init(void)

               if (end_pfn > max_low_pfn)
                       max_low_pfn = end_pfn;
+               if (end_pfn > start_pfn)
+                       node_set_state(node, N_NORMAL_MEMORY);
       }
       zones_size[ZONE_NORMAL] = max_low_pfn;
       free_area_init_nodes(zones_size);
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-- 
Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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
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