linux-kernel - [PATCH V2] mem-hotplug: let memblock skip the hotpluggable memory regions in __next_mem

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Message-ID: <53F15E37.9080602@huawei.com>
Date:	Mon, 18 Aug 2014 10:00:23 +0800
From:	Xishi Qiu <qiuxishi@...wei.com>
To:	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Tang Chen" <tangchen@...fujitsu.com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	Wen Congyang <wency@...fujitsu.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, "H. Peter Anvin" <hpa@...or.com>
CC:	Linux MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH V2] mem-hotplug: let memblock skip the hotpluggable memory
 regions in __next_mem_range()

Let memblock skip the hotpluggable memory regions in __next_mem_range(),
it is used to to prevent memblock from allocating hotpluggable memory 
for the kernel at early time. The code is the same as __next_mem_range_rev().

Clear hotpluggable flag before releasing free pages to the buddy allocator.
If we don't clear hotpluggable flag in free_low_memory_core_early(), the 
memory which marked hotpluggable flag will not free to buddy allocator.
Because __next_mem_range() will skip them.

free_low_memory_core_early
	for_each_free_mem_range
		for_each_mem_range
			__next_mem_range

Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>
---
 mm/memblock.c  |    4 ++++
 mm/nobootmem.c |    2 ++
 2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 6d2f219..5090050 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -817,6 +817,10 @@ void __init_memblock __next_mem_range(u64 *idx, int nid,
 		if (nid != NUMA_NO_NODE && nid != m_nid)
 			continue;
 
+		/* skip hotpluggable memory regions if needed */
+		if (movable_node_is_enabled() && memblock_is_hotpluggable(m))
+			continue;
+
 		if (!type_b) {
 			if (out_start)
 				*out_start = m_start;
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 7ed5860..03de286 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -119,6 +119,8 @@ static unsigned long __init free_low_memory_core_early(void)
 	phys_addr_t start, end;
 	u64 i;
 
+	memblock_clear_hotplug(0, ULLONG_MAX);
+
 	for_each_free_mem_range(i, NUMA_NO_NODE, &start, &end, NULL)
 		count += __free_memory_core(start, end);
 
-- 1.7.1 



. 

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