The patch titled
Subject: mm: don't panic when links can't be created in sysfs
has been added to the -mm tree. Its filename is
mm-dont-panic-when-links-cant-be-created-in-sysfs.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-dont-panic-when-links-cant-be-created-in-sysfs.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-dont-panic-when-links-cant-be-created-in-sysfs.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Subject: 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.
Link: https://lkml.kernel.org/r/20200915094143.79181-4-ldufour@xxxxxxxxxxxxx
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Cc: "Rafael J . Wysocki" <rafael@xxxxxxxxxx>
Cc: Scott Cheloha <cheloha@xxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/node.c | 33 +++++++++++++++++++++------------
include/linux/node.h | 16 +++++++---------
mm/memory_hotplug.c | 5 ++---
3 files changed, 30 insertions(+), 24 deletions(-)
--- a/drivers/base/node.c~mm-dont-panic-when-links-cant-be-created-in-sysfs
+++ a/drivers/base/node.c
@@ -761,8 +761,8 @@ static int __ref get_nid_for_pfn(unsigne
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;
@@ -775,12 +775,19 @@ static int do_register_memory_block_unde
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 */
@@ -816,7 +823,8 @@ static int register_mem_block_under_node
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;
@@ -831,7 +839,8 @@ static int register_mem_block_under_node
{
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;
}
/*
@@ -849,8 +858,8 @@ void unregister_memory_block_under_nodes
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;
@@ -859,9 +868,9 @@ int link_mem_sections(int nid, unsigned
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
--- a/include/linux/node.h~mm-dont-panic-when-links-cant-be-created-in-sysfs
+++ a/include/linux/node.h
@@ -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,
- 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);
#else
-static inline int link_mem_sections(int nid, unsigned long start_pfn,
- unsigned long end_pfn,
- enum meminit_context context)
+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
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;
--- a/mm/memory_hotplug.c~mm-dont-panic-when-links-cant-be-created-in-sysfs
+++ a/mm/memory_hotplug.c
@@ -1094,9 +1094,8 @@ int __ref add_memory_resource(int nid, s
}
/* link memory sections under this node.*/
- ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
- MEMINIT_HOTPLUG);
- BUG_ON(ret);
+ link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
+ MEMINIT_HOTPLUG);
/* create new memmap entry */
if (!strcmp(res->name, "System RAM"))
_
Patches currently in -mm which might be from ldufour@xxxxxxxxxxxxx are
mm-replace-memmap_context-by-meminit_context.patch
mm-dont-rely-on-system-state-to-detect-hot-plug-operations.patch
mm-dont-panic-when-links-cant-be-created-in-sysfs.patch
