Patch "mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

    mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}

to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_-begin-done.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dan Williams <[email protected]>
Date: Fri, 24 Feb 2017 14:55:45 -0800
Subject: mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}

From: Dan Williams <[email protected]>

commit b5d24fda9c3dce51fcb4eee459550a458eaaf1e2 upstream.

The mem_hotplug_{begin,done} lock coordinates with {get,put}_online_mems() to hold off "readers" of the current state of memory from new hotplug actions. mem_hotplug_begin() expects exclusive access, via the device_hotplug lock, to set mem_hotplug.active_writer. Calling mem_hotplug_begin() without locking device_hotplug can lead to corrupting mem_hotplug.refcount and missed wakeups / soft lockups.

---
 kernel/memremap.c |    6 ++++++
 1 file changed, 6 insertions(+)

@@ -246,9 +246,13 @@ static void devm_memremap_pages_release(
 	/* pages are dead and unused, undo the arch mapping */
 	align_start = res->start & ~(SECTION_SIZE - 1);
 	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+
+	lock_device_hotplug();
 	mem_hotplug_begin();
 	arch_remove_memory(align_start, align_size);
 	mem_hotplug_done();
+	unlock_device_hotplug();
+
 	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
 	pgmap_radix_release(res);
 	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,

@@ -360,9 +364,11 @@ void *devm_memremap_pages(struct device
 	if (error)
 		goto err_pfn_remap;
 
+	lock_device_hotplug();
 	mem_hotplug_begin();
 	error = arch_add_memory(nid, align_start, align_size, true);
 	mem_hotplug_done();
+	unlock_device_hotplug();
 	if (error)
 		goto err_add_memory;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_-begin-done.patch