The patch titled
Subject: mm: node_states: introduce N_MEMORY
has been added to the -mm tree. Its filename is
node_states-introduce-n_memory.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Subject: mm: node_states: introduce N_MEMORY
We have N_NORMAL_MEMORY for standing for the nodes that have normal memory
with zone_type <= ZONE_NORMAL.
And we have N_HIGH_MEMORY for standing for the nodes that have normal or
high memory.
But we don't have any word to stand for the nodes that have *any* memory.
And we have N_CPU but without N_MEMORY.
Current code reuse the N_HIGH_MEMORY for this purpose because any node
which has memory must have high memory or normal memory currently.
A) But this reusing is bad for *readability*. Because the name
N_HIGH_MEMORY just stands for high or normal:
A.example 1)
mem_cgroup_nr_lru_pages():
for_each_node_state(nid, N_HIGH_MEMORY)
The user will be confused(why this function just counts for high or
normal memory node? does it counts for ZONE_MOVABLE's lru pages?)
until someone else tell them N_HIGH_MEMORY is reused to stand for
nodes that have any memory.
A.cont) If we introduce N_MEMORY, we can reduce this confusing
AND make the code more clearly:
A.example 2) mm/page_cgroup.c use N_HIGH_MEMORY twice:
One is in page_cgroup_init(void):
for_each_node_state(nid, N_HIGH_MEMORY) {
It means if the node have memory, we will allocate page_cgroup map for
the node. We should use N_MEMORY instead here to gaim more clearly.
The second using is in alloc_page_cgroup():
if (node_state(nid, N_HIGH_MEMORY))
addr = vzalloc_node(size, nid);
It means if the node has high or normal memory that can be allocated
from kernel. We should keep N_HIGH_MEMORY here, and it will be better
if the "any memory" semantic of N_HIGH_MEMORY is removed.
B) This reusing is out-dated if we introduce MOVABLE-dedicated node.
The MOVABLE-dedicated node should not appear in
node_stats[N_HIGH_MEMORY] nor node_stats[N_NORMAL_MEMORY],
because MOVABLE-dedicated node has no high or normal memory.
In x86_64, N_HIGH_MEMORY=N_NORMAL_MEMORY, if a MOVABLE-dedicated node
is in node_stats[N_HIGH_MEMORY], it is also means it is in
node_stats[N_NORMAL_MEMORY], it causes SLUB wrong.
The slub uses
for_each_node_state(nid, N_NORMAL_MEMORY)
and creates kmem_cache_node for MOVABLE-dedicated node and cause problem.
In one word, we need a N_MEMORY. We just intrude it as an alias to
N_HIGH_MEMORY and fix all im-proper usages of N_HIGH_MEMORY in late
patches.
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Acked-by: Christoph Lameter <cl@xxxxxxxxx>
Acked-by: Hillf Danton <dhillf@xxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Lin Feng <linfeng@xxxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/nodemask.h | 1 +
1 file changed, 1 insertion(+)
diff -puN include/linux/nodemask.h~node_states-introduce-n_memory include/linux/nodemask.h
--- a/include/linux/nodemask.h~node_states-introduce-n_memory
+++ a/include/linux/nodemask.h
@@ -380,6 +380,7 @@ enum node_states {
#else
N_HIGH_MEMORY = N_NORMAL_MEMORY,
#endif
+ N_MEMORY = N_HIGH_MEMORY,
N_CPU, /* The node has one or more cpus */
NR_NODE_STATES
};
_
Patches currently in -mm which might be from laijs@xxxxxxxxxxxxxx are
linux-next.patch
memory_hotplug-fix-possible-incorrect-node_states.patch
slub-hotplug-ignore-unrelated-nodes-hot-adding-and-hot-removing.patch
drivers-base-nodec-cleanup-node_state_attr.patch
mm-memory-hotplug-dynamic-configure-movable-memory-and-portion-memory.patch
mm-memory-hotplug-dynamic-configure-movable-memory-and-portion-memory-fix.patch
memory_hotplug-handle-empty-zone-when-online_movable-online_kernel.patch
memory_hotplug-ensure-every-online-node-has-normal-memory.patch
node_states-introduce-n_memory.patch
cpuset-use-n_memory-instead-n_high_memory.patch
procfs-use-n_memory-instead-n_high_memory.patch
memcontrol-use-n_memory-instead-n_high_memory.patch
oom-use-n_memory-instead-n_high_memory.patch
mmmigrate-use-n_memory-instead-n_high_memory.patch
mempolicy-use-n_memory-instead-n_high_memory.patch
hugetlb-use-n_memory-instead-n_high_memory.patch
vmstat-use-n_memory-instead-n_high_memory.patch
kthread-use-n_memory-instead-n_high_memory.patch
init-use-n_memory-instead-n_high_memory.patch
vmscan-use-n_memory-instead-n_high_memory.patch
page_alloc-use-n_memory-instead-n_high_memory-change-the-node_states-initialization.patch
hotplug-update-nodemasks-management.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
