The patch titled
Subject: Bug fix: Hold spinlock across find|remove /sys/firmware/memmap/X operation.
has been added to the -mm tree. Its filename is
memory-hotplug-remove-sys-firmware-memmap-x-sysfs-fix.patch
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------------------------------------------------------
From: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Subject: Bug fix: Hold spinlock across find|remove /sys/firmware/memmap/X operation.
It is unsafe to return an entry pointer and release the map_entries_lock.
So we should not hold the map_entries_lock separately in
firmware_map_find_entry() and firmware_map_remove_entry(). Hold the
map_entries_lock across find and remove /sys/firmware/memmap/X operation.
And also, users of these two functions need to be careful to hold the lock
when using these two functions.
The suggestion is from Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/memmap.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
diff -puN drivers/firmware/memmap.c~memory-hotplug-remove-sys-firmware-memmap-x-sysfs-fix drivers/firmware/memmap.c
--- a/drivers/firmware/memmap.c~memory-hotplug-remove-sys-firmware-memmap-x-sysfs-fix
+++ a/drivers/firmware/memmap.c
@@ -150,12 +150,12 @@ static int firmware_map_add_entry(u64 st
* firmware_map_remove_entry() - Does the real work to remove a firmware
* memmap entry.
* @entry: removed entry.
+ *
+ * The caller must hold map_entries_lock, and release it properly.
**/
static inline void firmware_map_remove_entry(struct firmware_map_entry *entry)
{
- spin_lock(&map_entries_lock);
list_del(&entry->list);
- spin_unlock(&map_entries_lock);
}
/*
@@ -188,23 +188,28 @@ static inline void remove_sysfs_fw_map_e
}
/*
- * Search memmap entry
+ * firmware_map_find_entry: Search memmap entry.
+ * @start: Start of the memory range.
+ * @end: End of the memory range (exclusive).
+ * @type: Type of the memory range.
+ *
+ * This function is to find the memmap entey of a given memory range.
+ * The caller must hold map_entries_lock, and must not release the lock
+ * until the processing of the returned entry has completed.
+ *
+ * Return pointer to the entry to be found on success, or NULL on failure.
*/
-
static struct firmware_map_entry * __meminit
firmware_map_find_entry(u64 start, u64 end, const char *type)
{
struct firmware_map_entry *entry;
- spin_lock(&map_entries_lock);
list_for_each_entry(entry, &map_entries, list)
if ((entry->start == start) && (entry->end == end) &&
(!strcmp(entry->type, type))) {
- spin_unlock(&map_entries_lock);
return entry;
}
- spin_unlock(&map_entries_lock);
return NULL;
}
@@ -274,11 +279,15 @@ int __meminit firmware_map_remove(u64 st
{
struct firmware_map_entry *entry;
+ spin_lock(&map_entries_lock);
entry = firmware_map_find_entry(start, end - 1, type);
- if (!entry)
+ if (!entry) {
+ spin_unlock(&map_entries_lock);
return -EINVAL;
+ }
firmware_map_remove_entry(entry);
+ spin_unlock(&map_entries_lock);
/* remove the memmap entry */
remove_sysfs_fw_map_entry(entry);
_
Patches currently in -mm which might be from tangchen@xxxxxxxxxxxxxx are
memory-hotplug-try-to-offline-the-memory-twice-to-avoid-dependence.patch
memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory.patch
memory-hotplug-remove-redundant-codes.patch
memory-hotplug-remove-sys-firmware-memmap-x-sysfs.patch
memory-hotplug-remove-sys-firmware-memmap-x-sysfs-fix.patch
memory-hotplug-introduce-new-arch_remove_memory-for-removing-page-table.patch
memory-hotplug-implement-register_page_bootmem_info_section-of-sparse-vmemmap.patch
memory-hotplug-move-pgdat_resize_lock-into-sparse_remove_one_section.patch
memory-hotplug-common-apis-to-support-page-tables-hot-remove.patch
memory-hotplug-common-apis-to-support-page-tables-hot-remove-fix.patch
memory-hotplug-remove-page-table-of-x86_64-architecture.patch
memory-hotplug-remove-page-table-of-x86_64-architecture-fix.patch
memory-hotplug-remove-memmap-of-sparse-vmemmap.patch
memory-hotplug-integrated-__remove_section-of-config_sparsemem_vmemmap.patch
memory_hotplug-clear-zone-when-removing-the-memory.patch
memory-hotplug-remove-sysfs-file-of-node.patch
memory-hotplug-free-node_data-when-a-node-is-offlined.patch
memory-hotplug-do-not-allocate-pdgat-if-it-was-not-freed-when-offline.patch
x86-get-pg_data_ts-memory-from-other-node.patch
page_alloc-add-movable_memmap-kernel-parameter.patch
page_alloc-add-movable_memmap-kernel-parameter-fix.patch
page_alloc-introduce-zone_movable_limit-to-keep-movable-limit-for-nodes.patch
page_alloc-make-movablecore_map-has-higher-priority.patch
page_alloc-bootmem-limit-with-movablecore_map.patch
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