linux-kernel - Re: undefined reference to `node

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Message-ID: <YjxmrTKxRpTFeHnE@dhcp22.suse.cz>
Date:   Thu, 24 Mar 2022 13:40:13 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     kernel test robot <lkp@...el.com>, kbuild-all@...ts.01.org,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-kernel@...r.kernel.org, Oscar Salvador <osalvador@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linux-mips@...r.kernel.org
Subject: Re: undefined reference to `node_data'

On Thu 24-03-22 10:04:43, Thomas Bogendoerfer wrote:
> On Wed, Mar 23, 2022 at 05:46:59PM +0100, Michal Hocko wrote:
> > > > If you fix the issue, kindly add following tag as appropriate
> > > > Reported-by: kernel test robot <lkp@...el.com>
> > > > 
> > > > All errors (new ones prefixed by >>):
> > > > 
> > > >    mips64-linux-ld: mm/page_alloc.o: in function `free_area_init':
> > > > >> (.init.text+0x1680): undefined reference to `node_data'
> > > >    mips64-linux-ld: (.init.text+0x1690): undefined reference to `node_data'
> > > 
> > > OK, I can see what is going here. The page allocator normally
> > > uses NODE_DATA but arch_refresh_nodedata refers to node_data directly.
> > > This is a problem with
> > > arch/mips/include/asm/mach-loongson64/mmzone.h:
> > > extern struct pglist_data *__node_data[];
> > > 
> > > #define NODE_DATA(n)            (__node_data[n])
> > > 
> > > Unfortunately we cannot use NODE_DATA there because of header inclusion
> > > ordering. I will think about a solution.
> > 
> > Is there any reason why (some?) MIPS arches use __node_data rather than
> > node_data as most other architectures? Would it be acceptable to do the
> > renaming? It would help to cover the above compilation problem because
> > arch_refresh_nodedata could keep using node_data directly.
> 
> I've just checked history and I don't see a reason for __node_data.
> So I'm fine with changing it to node_data.

Thanks a lot for double checking Thomas! This is a dump&simple sed over
mips file. 0-day guys, could you give it a try please?
--- 
diff --git a/arch/mips/include/asm/mach-ip27/mmzone.h b/arch/mips/include/asm/mach-ip27/mmzone.h
index 08c36e50a860..a798ad379da1 100644
--- a/arch/mips/include/asm/mach-ip27/mmzone.h
+++ b/arch/mips/include/asm/mach-ip27/mmzone.h
@@ -20,9 +20,9 @@ struct node_data {
 	struct hub_data hub;
 };
 
-extern struct node_data *__node_data[];
+extern struct node_data *node_data[];
 
-#define NODE_DATA(n)		(&__node_data[(n)]->pglist)
-#define hub_data(n)		(&__node_data[(n)]->hub)
+#define NODE_DATA(n)		(&node_data[(n)]->pglist)
+#define hub_data(n)		(&node_data[(n)]->hub)
 
 #endif /* _ASM_MACH_MMZONE_H */
diff --git a/arch/mips/include/asm/mach-loongson64/mmzone.h b/arch/mips/include/asm/mach-loongson64/mmzone.h
index ebb1deaa77b9..14e2b860ad65 100644
--- a/arch/mips/include/asm/mach-loongson64/mmzone.h
+++ b/arch/mips/include/asm/mach-loongson64/mmzone.h
@@ -14,9 +14,9 @@
 #define pa_to_nid(addr)  (((addr) & 0xf00000000000) >> NODE_ADDRSPACE_SHIFT)
 #define nid_to_addrbase(nid) ((unsigned long)(nid) << NODE_ADDRSPACE_SHIFT)
 
-extern struct pglist_data *__node_data[];
+extern struct pglist_data *node_data[];
 
-#define NODE_DATA(n)		(__node_data[n])
+#define NODE_DATA(n)		(node_data[n])
 
 extern void setup_zero_pages(void);
 extern void __init prom_init_numa_memory(void);
diff --git a/arch/mips/loongson64/numa.c b/arch/mips/loongson64/numa.c
index e8e3e48c5333..abbbc70ce980 100644
--- a/arch/mips/loongson64/numa.c
+++ b/arch/mips/loongson64/numa.c
@@ -29,8 +29,8 @@
 
 unsigned char __node_distances[MAX_NUMNODES][MAX_NUMNODES];
 EXPORT_SYMBOL(__node_distances);
-struct pglist_data *__node_data[MAX_NUMNODES];
-EXPORT_SYMBOL(__node_data);
+struct pglist_data *node_data[MAX_NUMNODES];
+EXPORT_SYMBOL(node_data);
 
 cpumask_t __node_cpumask[MAX_NUMNODES];
 EXPORT_SYMBOL(__node_cpumask);
@@ -107,7 +107,7 @@ static void __init node_mem_init(unsigned int node)
 	tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
 	if (tnid != node)
 		pr_info("NODE_DATA(%d) on node %d\n", node, tnid);
-	__node_data[node] = nd;
+	node_data[node] = nd;
 	NODE_DATA(node)->node_start_pfn = start_pfn;
 	NODE_DATA(node)->node_spanned_pages = end_pfn - start_pfn;
 
diff --git a/arch/mips/sgi-ip27/ip27-memory.c b/arch/mips/sgi-ip27/ip27-memory.c
index adc2faeecf7c..1c3a0b92d134 100644
--- a/arch/mips/sgi-ip27/ip27-memory.c
+++ b/arch/mips/sgi-ip27/ip27-memory.c
@@ -33,9 +33,9 @@
 #define SLOT_PFNSHIFT		(SLOT_SHIFT - PAGE_SHIFT)
 #define PFN_NASIDSHFT		(NASID_SHFT - PAGE_SHIFT)
 
-struct node_data *__node_data[MAX_NUMNODES];
+struct node_data *node_data[MAX_NUMNODES];
 
-EXPORT_SYMBOL(__node_data);
+EXPORT_SYMBOL(node_data);
 
 static u64 gen_region_mask(void)
 {
@@ -358,8 +358,8 @@ static void __init node_mem_init(nasid_t node)
 	/*
 	 * Allocate the node data structures on the node first.
 	 */
-	__node_data[node] = __va(slot_freepfn << PAGE_SHIFT);
-	memset(__node_data[node], 0, PAGE_SIZE);
+	node_data[node] = __va(slot_freepfn << PAGE_SHIFT);
+	memset(node_data[node], 0, PAGE_SIZE);
 
 	NODE_DATA(node)->node_start_pfn = start_pfn;
 	NODE_DATA(node)->node_spanned_pages = end_pfn - start_pfn;
@@ -401,7 +401,7 @@ void __init prom_meminit(void)
 			node_mem_init(node);
 			continue;
 		}
-		__node_data[node] = &null_node;
+		node_data[node] = &null_node;
 	}
 }
-- 
Michal Hocko
SUSE Labs