Ingo Molnar wrote:
> * Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>
>> Andrew Morton wrote:
>>> On Mon, 22 Jun 2009 08:38:50 -0700
>>> Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>>>
>>>> Nathan reported that
>>>> | commit 73d60b7f747176dbdff826c4127d22e1fd3f9f74
>>>> | Author: Yinghai Lu <yinghai@xxxxxxxxxx>
>>>> | Date: Tue Jun 16 15:33:00 2009 -0700
>>>> |
>>>> | page-allocator: clear N_HIGH_MEMORY map before we set it again
>>>> |
>>>> | SRAT tables may contains nodes of very small size. The arch code may
>>>> | decide to not activate such a node. However, currently the early boot
>>>> | code sets N_HIGH_MEMORY for such nodes. These nodes therefore seem to be
>>>> | active although these nodes have no present pages.
>>>> |
>>>> | For 64bit N_HIGH_MEMORY == N_NORMAL_MEMORY, so that works for 64 bit too
>>>>
>>>> the cpuset.mems cgroup attribute on an i386 kvm guest
>>>>
>>>> fix it by only clearing node_states[N_NORMAL_MEMORY] for 64bit only.
>>>> and need to do save/restore for that in find_zone_movable_pfn
>>>>
>>> There appear to be some words omitted from this changelog - it doesn't
>>> make sense.
>>>
>>> I think that perhaps a line got deleted before "the cpuset.mems cgroup
>>> ...". That was the line which actualy describes the bug which we're
>>> fixing. Or perhaps it was a single word? "zeroes".
>>>
>>>
>>> I did this:
>>>
>>> Nathan reported that
>>> :
>>> : | commit 73d60b7f747176dbdff826c4127d22e1fd3f9f74
>>> : | Author: Yinghai Lu <yinghai@xxxxxxxxxx>
>>> : | Date: Tue Jun 16 15:33:00 2009 -0700
>>> : |
>>> : | page-allocator: clear N_HIGH_MEMORY map before we set it again
>>> : |
>>> : | SRAT tables may contains nodes of very small size. The arch code may
>>> : | decide to not activate such a node. However, currently the early boot
>>> : | code sets N_HIGH_MEMORY for such nodes. These nodes therefore seem to be
>>> : | active although these nodes have no present pages.
>>> : |
>>> : | For 64bit N_HIGH_MEMORY == N_NORMAL_MEMORY, so that works for 64 bit too
>>> :
>> "
>>> : unintentionally and incorrectly clears the cpuset.mems cgroup attribute on
>>> : an i386 kvm guest
>> "
>> ==>
>>
>> 32bit assume NORMAL_MEMORY bit and HIGH_MEMORY bit are set for
>> Node0 always.
>
> Where in the code is this assumption?
in mm/page_alloc.c
/*
* Array of node states.
*/
nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
[N_POSSIBLE] = NODE_MASK_ALL,
[N_ONLINE] = { { [0] = 1UL } },
#ifndef CONFIG_NUMA
[N_NORMAL_MEMORY] = { { [0] = 1UL } },
#ifdef CONFIG_HIGHMEM
[N_HIGH_MEMORY] = { { [0] = 1UL } },
#endif
[N_CPU] = { { [0] = 1UL } },
#endif /* NUMA */
};
EXPORT_SYMBOL(node_states);
for x86 64bit, we clear POSSIBLE and ONLINE in arch/x86/mm/numa_64.c::initmem_init
and this patch clear NORMAL in arch/x86/mm/init_64.c::paging_init
for x86 32bit: ONLINE get cleared in get_memcfg_from_srat()
and NORMAL and HIGH_MEMORY are not cleared
before try to set new in mm/page_alloc.c::free_area_init_nodes
>
>> and some code only check if HIGH_MEMORY is there to know if
>> NORMAL_MEMORY is there.
>
> Which code is that exactly?
>
with grep:
arch/x86/mm/init_64.c: nodes_clear(node_states[N_NORMAL_MEMORY]);
drivers/base/node.c: return print_nodes_state(N_NORMAL_MEMORY, buf);
include/linux/nodemask.h: N_NORMAL_MEMORY, /* The node has regular memory */
include/linux/nodemask.h: N_HIGH_MEMORY = 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)
Documentation/cgroups/cpusets.txt:automatically tracks the value of node_states[N_HIGH_MEMORY]--i.e.,
Documentation/memory-hotplug.txt:status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be)
arch/ia64/kernel/uncached.c: if (!node_state(nid, N_HIGH_MEMORY))
drivers/base/node.c: return print_nodes_state(N_HIGH_MEMORY, buf);
include/linux/cpuset.h:#define cpuset_current_mems_allowed (node_states[N_HIGH_MEMORY])
include/linux/nodemask.h: N_HIGH_MEMORY, /* The node has regular or high memory */
include/linux/nodemask.h: N_HIGH_MEMORY = N_NORMAL_MEMORY,
kernel/cpuset.c: * found any online mems, return node_states[N_HIGH_MEMORY].
kernel/cpuset.c: * of node_states[N_HIGH_MEMORY].
kernel/cpuset.c: node_states[N_HIGH_MEMORY]))
kernel/cpuset.c: node_states[N_HIGH_MEMORY]);
kernel/cpuset.c: *pmask = node_states[N_HIGH_MEMORY];
kernel/cpuset.c: BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY]));
kernel/cpuset.c: * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
kernel/cpuset.c: node_states[N_HIGH_MEMORY]))
kernel/cpuset.c: nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
kernel/cpuset.c: node_states[N_HIGH_MEMORY]);
kernel/cpuset.c: * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
kernel/cpuset.c: * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
kernel/cpuset.c: top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
kernel/cpuset.c: top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
kernel/cpuset.c: * subset of node_states[N_HIGH_MEMORY], even if this means going outside the
mm/memcontrol.c: for_each_node_state(node, N_HIGH_MEMORY) {
mm/memory_hotplug.c: node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
mm/mempolicy.c: if (!nodes_subset(new, node_states[N_HIGH_MEMORY])) {
mm/mempolicy.c: for_each_node_state(nid, N_HIGH_MEMORY) {
mm/mempolicy.c: if (!nodes_subset(nodes, node_states[N_HIGH_MEMORY]))
mm/mempolicy.c: nodes = node_states[N_HIGH_MEMORY];
mm/mempolicy.c: &node_states[N_HIGH_MEMORY], MPOL_MF_STATS, md);
mm/mempolicy.c: for_each_node_state(n, N_HIGH_MEMORY)
mm/migrate.c: if (!node_state(node, N_HIGH_MEMORY))
mm/oom_kill.c: nodemask_t nodes = node_states[N_HIGH_MEMORY];
mm/page-writeback.c: for_each_node_state(node, N_HIGH_MEMORY) {
mm/page_alloc.c: [N_HIGH_MEMORY] = { { [0] = 1UL } },
mm/page_alloc.c: * tasks mems_allowed, or node_states[N_HIGH_MEMORY].)
mm/page_alloc.c: &node_states[N_HIGH_MEMORY];
mm/page_alloc.c: for_each_node_state(n, N_HIGH_MEMORY) {
mm/page_alloc.c: (nodes_weight(node_states[N_HIGH_MEMORY]) + 1);
mm/page_alloc.c: * Populate N_HIGH_MEMORY for calculating usable_nodes.
mm/page_alloc.c: node_set_state(early_node_map[i].nid, N_HIGH_MEMORY);
mm/page_alloc.c: nodemask_t saved_node_state = node_states[N_HIGH_MEMORY];
mm/page_alloc.c: int usable_nodes = nodes_weight(node_states[N_HIGH_MEMORY]);
mm/page_alloc.c: for_each_node_state(nid, N_HIGH_MEMORY) {
mm/page_alloc.c: node_states[N_HIGH_MEMORY] = saved_node_state;
mm/page_alloc.c: node_set_state(nid, N_HIGH_MEMORY);
mm/vmalloc.c: for_each_node_state(nr, N_HIGH_MEMORY)
mm/vmscan.c: for_each_node_state(nid, N_HIGH_MEMORY) {
mm/vmscan.c: for_each_node_state(nid, N_HIGH_MEMORY)
mm/vmstat.c: if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
for 64bit N_HIGH_MEMORY == NORMAL_MEMORY
for 32bit, there are more reference to N_HIGH_MEMORY...
YH
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