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Date: Wed, 24 May 2017 15:42:37 +0200
From: Michal Hocko <mhocko@...nel.org>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>,
Andrea Arcangeli <aarcange@...hat.com>,
Jerome Glisse <jglisse@...hat.com>,
Reza Arbab <arbab@...ux.vnet.ibm.com>,
Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
David Rientjes <rientjes@...gle.com>,
Daniel Kiper <daniel.kiper@...cle.com>,
Igor Mammedov <imammedo@...hat.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/2] mm, memory_hotplug: drop CONFIG_MOVABLE_NODE
On Wed 24-05-17 14:53:57, Vlastimil Babka wrote:
> On 05/24/2017 02:24 PM, Michal Hocko wrote:
[...]
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index facc20a3f962..ec7d6ae01c96 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -2246,8 +2246,11 @@
> > that the amount of memory usable for all allocations
> > is not too small.
> >
> > - movable_node [KNL] Boot-time switch to enable the effects
> > - of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details.
> > + movable_node [KNL] Boot-time switch to make hotplugable to be
>
> hotplugable what, memory? nodes?
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ec7d6ae01c96..64aed7386fe4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2246,11 +2246,11 @@
that the amount of memory usable for all allocations
is not too small.
- movable_node [KNL] Boot-time switch to make hotplugable to be
- movable. This means that the memory of such nodes
- will be usable only for movable allocations which
- rules out almost all kernel allocations. Use with
- caution!
+ movable_node [KNL] Boot-time switch to make hotplugable memory
+ NUMA nodes to be movable. This means that the memory
+ of such nodes will be usable only for movable
+ allocations which rules out almost all kernel
+ allocations. Use with caution!
MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
Better?
[...]
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -149,32 +149,6 @@ config NO_BOOTMEM
> > config MEMORY_ISOLATION
> > bool
> >
> > -config MOVABLE_NODE
> > - bool "Enable to assign a node which has only movable memory"
> > - depends on HAVE_MEMBLOCK
> > - depends on NO_BOOTMEM
> > - depends on X86_64 || OF_EARLY_FLATTREE || MEMORY_HOTPLUG
> > - depends on NUMA
>
> That's a lot of depends. What happens if some of them are not met and
> the movable_node bootparam is used?
Good question. I haven't explored that, to be honest. Now that I am looking closer
I am not even sure why all those dependencies are thre. MEMORY_HOTPLUG
is clear and OF_EARLY_FLATTREE is explained by 41a9ada3e6b4 ("of/fdt:
mark hotpluggable memory"). NUMA is less clear to me because
MEMORY_HOTPLUG doesn't really depend on NUMA systems. Dependency on
NO_BOOTMEM is also not clear to me because zones layout
doesn't really depend on the specific boot time allocator.
So we are left with HAVE_MEMBLOCK which seems to be there because
movable_node_enabled is defined there while the parameter handling is in
the hotplug proper. But there is no real reason to have it like that.
This compiles but I will have to put throw my full compile battery on it
to be sure. I will make it a separate patch.
Thanks!
---
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 9622fb8c101b..071692894254 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -57,8 +57,6 @@ struct memblock {
extern struct memblock memblock;
extern int memblock_debug;
-/* If movable_node boot option specified */
-extern bool movable_node_enabled;
#ifdef CONFIG_ARCH_DISCARD_MEMBLOCK
#define __init_memblock __meminit
@@ -171,11 +169,6 @@ static inline bool memblock_is_hotpluggable(struct memblock_region *m)
return m->flags & MEMBLOCK_HOTPLUG;
}
-static inline bool __init_memblock movable_node_is_enabled(void)
-{
- return movable_node_enabled;
-}
-
static inline bool memblock_is_mirror(struct memblock_region *m)
{
return m->flags & MEMBLOCK_MIRROR;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 9e0249d0f5e4..9c1ac94f857b 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -115,6 +115,12 @@ extern void __online_page_free(struct page *page);
extern int try_online_node(int nid);
extern bool memhp_auto_online;
+/* If movable_node boot option specified */
+extern bool movable_node_enabled;
+static inline bool movable_node_is_enabled(void)
+{
+ return movable_node_enabled;
+}
#ifdef CONFIG_MEMORY_HOTREMOVE
extern bool is_pageblock_removable_nolock(struct page *page);
@@ -266,6 +272,10 @@ static inline void put_online_mems(void) {}
static inline void mem_hotplug_begin(void) {}
static inline void mem_hotplug_done(void) {}
+static inline bool __init_memblock movable_node_is_enabled(void)
+{
+ return false;
+}
#endif /* ! CONFIG_MEMORY_HOTPLUG */
#ifdef CONFIG_MEMORY_HOTREMOVE
diff --git a/mm/memblock.c b/mm/memblock.c
index 4895f5a6cf7e..8c52fb11510c 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -54,7 +54,6 @@ struct memblock memblock __initdata_memblock = {
};
int memblock_debug __initdata_memblock;
-bool movable_node_enabled __initdata_memblock = false;
static bool system_has_some_mirror __initdata_memblock = false;
static int memblock_can_resize __initdata_memblock;
static int memblock_memory_in_slab __initdata_memblock = 0;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2a14f8c18a22..b0d2bf3256d0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -79,6 +79,8 @@ static struct {
#define memhp_lock_acquire() lock_map_acquire(&mem_hotplug.dep_map)
#define memhp_lock_release() lock_map_release(&mem_hotplug.dep_map)
+bool movable_node_enabled = false;
+
#ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
bool memhp_auto_online;
#else
--
Michal Hocko
SUSE Labs
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