Commit 90c7eaeb authored by Laurent Dufour's avatar Laurent Dufour Committed by Linus Torvalds
Browse files

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: default avatarLaurent Dufour <ldufour@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarOscar Salvador <osalvador@suse.de>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200915094143.79181-4-ldufour@linux.ibm.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cb8e3c8b

drivers/base/node.c

+21 −12
Original line number Diff line number Diff line
@@ -772,7 +772,7 @@ 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,

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;

}



/*
@@ -860,7 +869,7 @@ 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,

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

include/linux/node.h

+7 −9
Original line number Diff line number Diff line
@@ -99,15 +99,14 @@ extern struct node *node_devices[]; 
typedef  void (*node_registration_func_t)(struct node *);



#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA)

int link_mem_sections(int nid, unsigned long start_pfn,

void link_mem_sections(int nid, unsigned long start_pfn,

		       unsigned long end_pfn,

		       enum meminit_context context);

#else

static inline int link_mem_sections(int nid, unsigned long start_pfn,

static inline void link_mem_sections(int nid, unsigned long start_pfn,

				     unsigned long end_pfn,

				     enum meminit_context context)

{

	return 0;

}

#endif
@@ -130,8 +129,7 @@ static inline int register_one_node(int nid) 
		if (error)

			return error;

		/* link memory sections under this node */

		error = link_mem_sections(nid, start_pfn, end_pfn,

					  MEMINIT_EARLY);

		link_mem_sections(nid, start_pfn, end_pfn, MEMINIT_EARLY);

	}



	return error;

mm/memory_hotplug.c

+2 −3
Original line number Diff line number Diff line
@@ -1092,9 +1092,8 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags) 
	}



	/* link memory sections under this node.*/

	ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),

	link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),

			  MEMINIT_HOTPLUG);

	BUG_ON(ret);



	/* create new memmap entry */

	if (!strcmp(res->name, "System RAM"))

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