The patch titled
Subject: mm, memory-hotplug: rework unregister_mem_sect_under_nodes
has been added to the -mm tree. Its filename is
mm-memory-hotplug-rework-unregister_mem_sect_under_nodes.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory-hotplug-rework-unregister_mem_sect_under_nodes.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory-hotplug-rework-unregister_mem_sect_under_nodes.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Oscar Salvador <osalvador@xxxxxxxx>
Subject: mm, memory-hotplug: rework unregister_mem_sect_under_nodes
This tries to address another issue about accessing unitiliazed pages.
Jonathan reported a problem [1] where we can access steal pages in case we
hot-remove memory without onlining it first.
This time is in unregister_mem_sect_under_nodes. This function tries to
get the nid from the pfn and then tries to remove the symlink between
mem_blk <-> nid and vice versa.
Since we already know the nid in remove_memory(), we can pass it down the
chain to unregister_mem_sect_under_nodes. There we can just remove the
symlinks without the need to look into the pages.
This also allows us to cleanup unregister_mem_sect_under_nodes.
[1] https://www.spinics.net/lists/linux-mm/msg161316.html
Link: http://lkml.kernel.org/r/20181127162005.15833-5-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Tested-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/drivers/base/memory.c~mm-memory-hotplug-rework-unregister_mem_sect_under_nodes
+++ a/drivers/base/memory.c
@@ -744,8 +744,7 @@ unregister_memory(struct memory_block *m
device_unregister(&memory->dev);
}
-static int remove_memory_section(unsigned long node_id,
- struct mem_section *section, int phys_device)
+static int remove_memory_section(unsigned long nid, struct mem_section *section)
{
struct memory_block *mem;
@@ -759,7 +758,7 @@ static int remove_memory_section(unsigne
if (!mem)
goto out_unlock;
- unregister_mem_sect_under_nodes(mem, __section_nr(section));
+ unregister_mem_sect_under_nodes(nid, mem);
mem->section_count--;
if (mem->section_count == 0)
@@ -772,12 +771,12 @@ out_unlock:
return 0;
}
-int unregister_memory_section(struct mem_section *section)
+int unregister_memory_section(int nid, struct mem_section *section)
{
if (!present_section(section))
return -EINVAL;
- return remove_memory_section(0, section, 0);
+ return remove_memory_section(nid, section);
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
--- a/drivers/base/node.c~mm-memory-hotplug-rework-unregister_mem_sect_under_nodes
+++ a/drivers/base/node.c
@@ -453,40 +453,13 @@ int register_mem_sect_under_node(struct
return 0;
}
-/* unregister memory section under all nodes that it spans */
-int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
- unsigned long phys_index)
+/* Remove symlink between node <-> mem_blk */
+void unregister_mem_sect_under_nodes(int nid, struct memory_block *mem_blk)
{
- NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
- unsigned long pfn, sect_start_pfn, sect_end_pfn;
-
- if (!mem_blk) {
- NODEMASK_FREE(unlinked_nodes);
- return -EFAULT;
- }
- if (!unlinked_nodes)
- return -ENOMEM;
- nodes_clear(*unlinked_nodes);
-
- sect_start_pfn = section_nr_to_pfn(phys_index);
- sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
- for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
- int nid;
-
- nid = get_nid_for_pfn(pfn);
- if (nid < 0)
- continue;
- if (!node_online(nid))
- continue;
- if (node_test_and_set(nid, *unlinked_nodes))
- continue;
- sysfs_remove_link(&node_devices[nid]->dev.kobj,
- kobject_name(&mem_blk->dev.kobj));
- sysfs_remove_link(&mem_blk->dev.kobj,
- kobject_name(&node_devices[nid]->dev.kobj));
- }
- NODEMASK_FREE(unlinked_nodes);
- return 0;
+ sysfs_remove_link(&node_devices[nid]->dev.kobj,
+ kobject_name(&mem_blk->dev.kobj));
+ sysfs_remove_link(&mem_blk->dev.kobj,
+ kobject_name(&node_devices[nid]->dev.kobj));
}
int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn)
--- a/include/linux/memory.h~mm-memory-hotplug-rework-unregister_mem_sect_under_nodes
+++ a/include/linux/memory.h
@@ -113,7 +113,7 @@ extern int register_memory_isolate_notif
extern void unregister_memory_isolate_notifier(struct notifier_block *nb);
int hotplug_memory_register(int nid, struct mem_section *section);
#ifdef CONFIG_MEMORY_HOTREMOVE
-extern int unregister_memory_section(struct mem_section *);
+extern int unregister_memory_section(int nid, struct mem_section *);
#endif
extern int memory_dev_init(void);
extern int memory_notify(unsigned long val, void *v);
--- a/include/linux/node.h~mm-memory-hotplug-rework-unregister_mem_sect_under_nodes
+++ a/include/linux/node.h
@@ -72,8 +72,8 @@ extern int register_cpu_under_node(unsig
extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
extern int register_mem_sect_under_node(struct memory_block *mem_blk,
void *arg);
-extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
- unsigned long phys_index);
+extern void unregister_mem_sect_under_nodes(int nid,
+ struct memory_block *mem_blk);
#ifdef CONFIG_HUGETLBFS
extern void register_hugetlbfs_with_node(node_registration_func_t doregister,
@@ -105,10 +105,9 @@ static inline int register_mem_sect_unde
{
return 0;
}
-static inline int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
- unsigned long phys_index)
+static inline void unregister_mem_sect_under_nodes(int nid,
+ struct memory_block *mem_blk)
{
- return 0;
}
static inline void register_hugetlbfs_with_node(node_registration_func_t reg,
--- a/mm/memory_hotplug.c~mm-memory-hotplug-rework-unregister_mem_sect_under_nodes
+++ a/mm/memory_hotplug.c
@@ -544,7 +544,7 @@ static int __remove_section(int nid, str
if (!valid_section(ms))
return ret;
- ret = unregister_memory_section(ms);
+ ret = unregister_memory_section(nid, ms);
if (ret)
return ret;
_
Patches currently in -mm which might be from osalvador@xxxxxxxx are
mm-memory_hotplug-add-nid-parameter-to-arch_remove_memory.patch
mm-memory_hotplug-move-zone-pages-handling-to-offline-stage.patch
mm-memory-hotplug-rework-unregister_mem_sect_under_nodes.patch
mm-memory_hotplug-refactor-shrink_zone-pgdat_span.patch
