[Devel] [PATCH RH7 1/2] backport: arch/x86/mm/numa.c: fix boot failure when all nodes are hotpluggable

[Dmitry Safonov]

From: Xishi Qiu <qiuxishi at huawei.com>
commit bd5cfb8977fbb49d9350f7c81cf1516142e35a6a
arch/x86/mm/numa.c: fix boot failure when all nodes are hotpluggable

If all the nodes are marked hotpluggable, alloc node data will fail.
Because __next_mem_range_rev() will skip the hotpluggable memory
regions.  numa_clear_kernel_node_hotplug() is called after alloc node
data.

numa_init()
    ...
    ret = init_func();  // this will mark hotpluggable flag from SRAT
    ...
    memblock_set_bottom_up(false);
    ...
    ret = numa_register_memblks(&numa_meminfo);  // this will alloc node data(pglist_data)
    ...
    numa_clear_kernel_node_hotplug();  // in case all the nodes are hotpluggable
    ...

numa_register_memblks()
    setup_node_data()
        memblock_find_in_range_node()
            __memblock_find_range_top_down()
                for_each_mem_range_rev()
                    __next_mem_range_rev()

This patch moves numa_clear_kernel_node_hotplug() into
numa_register_memblks(), clear kernel node hotpluggable flag before
alloc node data, then alloc node data won't fail even all the nodes
are hotpluggable.

[akpm at linux-foundation.org: coding-style fixes]
Signed-off-by: Xishi Qiu <qiuxishi at huawei.com>
Cc: Dave Jones <davej at redhat.com>
Cc: Tang Chen <tangchen at cn.fujitsu.com>
Cc: Gu Zheng <guz.fnst at cn.fujitsu.com>
Cc: Ingo Molnar <mingo at elte.hu>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

[backport from mainline]
https://jira.sw.ru/browse/PSBM-43010
Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
 arch/x86/mm/numa.c | 89 +++++++++++++++++++++++++++---------------------------
 1 file changed, 45 insertions(+), 44 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 9e0f45e..f11060b 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -473,6 +473,42 @@ static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
 	return true;
 }
 
+static void __init numa_clear_kernel_node_hotplug(void)
+{
+	int i, nid;
+	nodemask_t numa_kernel_nodes = NODE_MASK_NONE;
+	unsigned long start, end;
+	struct memblock_region *r;
+
+	/*
+	 * At this time, all memory regions reserved by memblock are
+	 * used by the kernel. Set the nid in memblock.reserved will
+	 * mark out all the nodes the kernel resides in.
+	 */
+	for (i = 0; i < numa_meminfo.nr_blks; i++) {
+		struct numa_memblk *mb = &numa_meminfo.blk[i];
+
+		memblock_set_node(mb->start, mb->end - mb->start,
+				  &memblock.reserved, mb->nid);
+	}
+
+	/* Mark all kernel nodes. */
+	for_each_memblock(reserved, r)
+		node_set(r->nid, numa_kernel_nodes);
+
+	/* Clear MEMBLOCK_HOTPLUG flag for memory in kernel nodes. */
+	for (i = 0; i < numa_meminfo.nr_blks; i++) {
+		nid = numa_meminfo.blk[i].nid;
+		if (!node_isset(nid, numa_kernel_nodes))
+			continue;
+
+		start = numa_meminfo.blk[i].start;
+		end = numa_meminfo.blk[i].end;
+
+		memblock_clear_hotplug(start, end - start);
+	}
+}
+
 static int __init numa_register_memblks(struct numa_meminfo *mi)
 {
 	unsigned long uninitialized_var(pfn_align);
@@ -491,6 +527,15 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
 	}
 
 	/*
+	 * At very early time, the kernel have to use some memory such as
+	 * loading the kernel image. We cannot prevent this anyway. So any
+	 * node the kernel resides in should be un-hotpluggable.
+	 *
+	 * And when we come here, alloc node data won't fail.
+	 */
+	numa_clear_kernel_node_hotplug();
+
+	/*
 	 * If sections array is gonna be used for pfn -> nid mapping, check
 	 * whether its granularity is fine enough.
 	 */
@@ -549,41 +594,6 @@ static void __init numa_init_array(void)
 	}
 }
 
-static void __init numa_clear_kernel_node_hotplug(void)
-{
-	int i, nid;
-	nodemask_t numa_kernel_nodes = NODE_MASK_NONE;
-	unsigned long start, end;
-	struct memblock_type *type = &memblock.reserved;
-
-	/*
-	 * At this time, all memory regions reserved by memblock are
-	 * used by the kernel. Set the nid in memblock.reserved will
-	 * mark out all the nodes the kernel resides in.
-	 */
-	for (i = 0; i < numa_meminfo.nr_blks; i++) {
-		struct numa_memblk *mb = &numa_meminfo.blk[i];
-		memblock_set_node(mb->start, mb->end - mb->start,
-				  &memblock.reserved, mb->nid);
-	}
-
-	/* Mark all kernel nodes. */
-	for (i = 0; i < type->cnt; i++)
-		node_set(type->regions[i].nid, numa_kernel_nodes);
-
-	/* Clear MEMBLOCK_HOTPLUG flag for memory in kernel nodes. */
-	for (i = 0; i < numa_meminfo.nr_blks; i++) {
-		nid = numa_meminfo.blk[i].nid;
-		if (!node_isset(nid, numa_kernel_nodes))
-			continue;
-
-		start = numa_meminfo.blk[i].start;
-		end = numa_meminfo.blk[i].end;
-
-		memblock_clear_hotplug(start, end - start);
-	}
-}
-
 static int __init numa_init(int (*init_func)(void))
 {
 	int i;
@@ -638,15 +648,6 @@ static int __init numa_init(int (*init_func)(void))
 	}
 	numa_init_array();
 
-	/*
-	 * At very early time, the kernel have to use some memory such as
-	 * loading the kernel image. We cannot prevent this anyway. So any
-	 * node the kernel resides in should be un-hotpluggable.
-	 *
-	 * And when we come here, numa_init() won't fail.
-	 */
-	numa_clear_kernel_node_hotplug();
-
 	return 0;
 }
 
-- 
2.7.0