[merged] mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock.patch removed from -mm tree

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The patch titled
     Subject: mm/memory_hotplug: make add_memory() take the device_hotplug_lock
has been removed from the -mm tree.  Its filename was
     mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/memory_hotplug: make add_memory() take the device_hotplug_lock

add_memory() currently does not take the device_hotplug_lock, however
is aleady called under the lock from
	arch/powerpc/platforms/pseries/hotplug-memory.c
	drivers/acpi/acpi_memhotplug.c
to synchronize against CPU hot-remove and similar.

In general, we should hold the device_hotplug_lock when adding memory to
synchronize against online/offline request (e.g.  from user space) - which
already resulted in lock inversions due to device_lock() and
mem_hotplug_lock - see 30467e0b3be ("mm, hotplug: fix concurrent memory
hot-add deadlock").  add_memory()/add_memory_resource() will create memory
block devices, so this really feels like the right thing to do.

Holding the device_hotplug_lock makes sure that a memory block device
can really only be accessed (e.g. via .online/.state) from user space,
once the memory has been fully added to the system.

The lock is not held yet in
	drivers/xen/balloon.c
	arch/powerpc/platforms/powernv/memtrace.c
	drivers/s390/char/sclp_cmd.c
	drivers/hv/hv_balloon.c
So, let's either use the locked variants or take the lock.

Don't export add_memory_resource(), as it once was exported to be used by
XEN, which is never built as a module.  If somebody requires it, we also
have to export a locked variant (as device_hotplug_lock is never
exported).

Link: http://lkml.kernel.org/r/20180925091457.28651-3-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Rashmica Gupta <rashmica.g@xxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Nathan Fontenot <nfont@xxxxxxxxxxxxxxxxxx>
Cc: John Allen <jallen@xxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
Cc: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@xxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx>
Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Philippe Ombredanne <pombredanne@xxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/powerpc/platforms/pseries/hotplug-memory.c |    2 -
 drivers/acpi/acpi_memhotplug.c                  |    2 -
 drivers/base/memory.c                           |    9 ++++-
 drivers/xen/balloon.c                           |    3 +
 include/linux/memory_hotplug.h                  |    1 
 mm/memory_hotplug.c                             |   22 ++++++++++++--
 6 files changed, 32 insertions(+), 7 deletions(-)

--- a/arch/powerpc/platforms/pseries/hotplug-memory.c~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -668,7 +668,7 @@ static int dlpar_add_lmb(struct drmem_lm
 	nid = memory_add_physaddr_to_nid(lmb->base_addr);
 
 	/* Add the memory */
-	rc = add_memory(nid, lmb->base_addr, block_sz);
+	rc = __add_memory(nid, lmb->base_addr, block_sz);
 	if (rc) {
 		invalidate_lmb_associativity_index(lmb);
 		return rc;
--- a/drivers/acpi/acpi_memhotplug.c~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/drivers/acpi/acpi_memhotplug.c
@@ -228,7 +228,7 @@ static int acpi_memory_enable_device(str
 		if (node < 0)
 			node = memory_add_physaddr_to_nid(info->start_addr);
 
-		result = add_memory(node, info->start_addr, info->length);
+		result = __add_memory(node, info->start_addr, info->length);
 
 		/*
 		 * If the memory block has been used by the kernel, add_memory()
--- a/drivers/base/memory.c~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/drivers/base/memory.c
@@ -519,15 +519,20 @@ memory_probe_store(struct device *dev, s
 	if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
 		return -EINVAL;
 
+	ret = lock_device_hotplug_sysfs();
+	if (ret)
+		goto out;
+
 	nid = memory_add_physaddr_to_nid(phys_addr);
-	ret = add_memory(nid, phys_addr,
-			 MIN_MEMORY_BLOCK_SIZE * sections_per_block);
+	ret = __add_memory(nid, phys_addr,
+			   MIN_MEMORY_BLOCK_SIZE * sections_per_block);
 
 	if (ret)
 		goto out;
 
 	ret = count;
 out:
+	unlock_device_hotplug();
 	return ret;
 }
 
--- a/drivers/xen/balloon.c~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/drivers/xen/balloon.c
@@ -395,7 +395,10 @@ static enum bp_state reserve_additional_
 	 * callers drop the mutex before trying again.
 	 */
 	mutex_unlock(&balloon_mutex);
+	/* add_memory_resource() requires the device_hotplug lock */
+	lock_device_hotplug();
 	rc = add_memory_resource(nid, resource, memhp_auto_online);
+	unlock_device_hotplug();
 	mutex_lock(&balloon_mutex);
 
 	if (rc) {
--- a/include/linux/memory_hotplug.h~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/include/linux/memory_hotplug.h
@@ -324,6 +324,7 @@ static inline void __remove_memory(int n
 extern void __ref free_area_init_core_hotplug(int nid);
 extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
 		void *arg, int (*func)(struct memory_block *, void *));
+extern int __add_memory(int nid, u64 start, u64 size);
 extern int add_memory(int nid, u64 start, u64 size);
 extern int add_memory_resource(int nid, struct resource *resource, bool online);
 extern int arch_add_memory(int nid, u64 start, u64 size,
--- a/mm/memory_hotplug.c~mm-memory_hotplug-make-add_memory-take-the-device_hotplug_lock
+++ a/mm/memory_hotplug.c
@@ -1068,7 +1068,12 @@ static int online_memory_block(struct me
 	return device_online(&mem->dev);
 }
 
-/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
+/*
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations (triggered e.g. by sysfs).
+ *
+ * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
+ */
 int __ref add_memory_resource(int nid, struct resource *res, bool online)
 {
 	u64 start, size;
@@ -1137,9 +1142,9 @@ out:
 	mem_hotplug_done();
 	return ret;
 }
-EXPORT_SYMBOL_GPL(add_memory_resource);
 
-int __ref add_memory(int nid, u64 start, u64 size)
+/* requires device_hotplug_lock, see add_memory_resource() */
+int __ref __add_memory(int nid, u64 start, u64 size)
 {
 	struct resource *res;
 	int ret;
@@ -1153,6 +1158,17 @@ int __ref add_memory(int nid, u64 start,
 		release_memory_resource(res);
 	return ret;
 }
+
+int add_memory(int nid, u64 start, u64 size)
+{
+	int rc;
+
+	lock_device_hotplug();
+	rc = __add_memory(nid, start, size);
+	unlock_device_hotplug();
+
+	return rc;
+}
 EXPORT_SYMBOL_GPL(add_memory);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
_

Patches currently in -mm which might be from david@xxxxxxxxxx are





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