mm: don't panic when links can't be created in sysfs

At boot time, or when doing memory hot-add operations, if the links in
sysfs can't be created, the system is still able to run, so just report
the error in the kernel log rather than BUG_ON and potentially make system
unusable because the callpath can be called with locks held.

Since the number of memory blocks managed could be high, the messages are
rate limited.

As a consequence, link_mem_sections() has no status to report anymore.

Signed-off-by: Laurent Dufour <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: "Rafael J . Wysocki" <[email protected]>
Cc: Scott Cheloha <[email protected]>
Cc: Tony Luck <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 21 insertions, 12 deletions

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 43d21f9e88b1..6ffa470e2984 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -772,8 +772,8 @@ static int __ref get_nid_for_pfn(unsigned long pfn)
 	return pfn_to_nid(pfn);
 }
 
-static int do_register_memory_block_under_node(int nid,
-					       struct memory_block *mem_blk)
+static void do_register_memory_block_under_node(int nid,
+						struct memory_block *mem_blk)
 {
 	int ret;
 
@@ -786,12 +786,19 @@ static int do_register_memory_block_under_node(int nid,
 	ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
 				       &mem_blk->dev.kobj,
 				       kobject_name(&mem_blk->dev.kobj));
-	if (ret)
-		return ret;
+	if (ret && ret != -EEXIST)
+		dev_err_ratelimited(&node_devices[nid]->dev,
+				    "can't create link to %s in sysfs (%d)\n",
+				    kobject_name(&mem_blk->dev.kobj), ret);
 
-	return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
+	ret = sysfs_create_link_nowarn(&mem_blk->dev.kobj,
 				&node_devices[nid]->dev.kobj,
 				kobject_name(&node_devices[nid]->dev.kobj));
+	if (ret && ret != -EEXIST)
+		dev_err_ratelimited(&mem_blk->dev,
+				    "can't create link to %s in sysfs (%d)\n",
+				    kobject_name(&node_devices[nid]->dev.kobj),
+				    ret);
 }
 
 /* register memory section under specified node if it spans that node */
@@ -827,7 +834,8 @@ static int register_mem_block_under_node_early(struct memory_block *mem_blk,
 		if (page_nid != nid)
 			continue;
 
-		return do_register_memory_block_under_node(nid, mem_blk);
+		do_register_memory_block_under_node(nid, mem_blk);
+		return 0;
 	}
 	/* mem section does not span the specified node */
 	return 0;
@@ -842,7 +850,8 @@ static int register_mem_block_under_node_hotplug(struct memory_block *mem_blk,
 {
 	int nid = *(int *)arg;
 
-	return do_register_memory_block_under_node(nid, mem_blk);
+	do_register_memory_block_under_node(nid, mem_blk);
+	return 0;
 }
 
 /*
@@ -860,8 +869,8 @@ void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
 			  kobject_name(&node_devices[mem_blk->nid]->dev.kobj));
 }
 
-int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn,
-		      enum meminit_context context)
+void link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn,
+		       enum meminit_context context)
 {
 	walk_memory_blocks_func_t func;
 
@@ -870,9 +879,9 @@ int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn,
 	else
 		func = register_mem_block_under_node_early;
 
-	return walk_memory_blocks(PFN_PHYS(start_pfn),
-				  PFN_PHYS(end_pfn - start_pfn), (void *)&nid,
-				  func);
+	walk_memory_blocks(PFN_PHYS(start_pfn), PFN_PHYS(end_pfn - start_pfn),
+			   (void *)&nid, func);
+	return;
 }
 
 #ifdef CONFIG_HUGETLBFS